An Etymological Dictionary of Astronomy and Astrophysics

1a) A surviving mark, sign, or evidence of the former existence, influence, or action of some agent or event; vestige.

1b) A barely discernible indication or evidence of some quantity, quality, characteristic, expression, etc.

1c) An extremely small amount of some chemical component (Dictionary.com).

1d) Math.: → trace of a matrix.

2a) To follow the footprints, track, or traces of.

2b) To follow, make out, or determine the course or line of, especially by going backward from the latest evidence, nearest existence, etc. (Dictionary.com).

Etymology (EN): M.E. tracen, from M.Fr. tracier, from V.L. *tractiare “delineate, score, trace,” from L. tractus “track, course,” literally “a drawing out,” from p.p. stem of trahere “to pull, draw.”

Etymology (PE): Gilaki mâle “mark, trace, fingerprint; scar,” pâ mâle “footprint,” gaz mâle “bite mark;” Aftari mâl “trace, mark,” pae mâl “footprint,” ponjé mâl “mark of hand with fingers;” Tabari mâl “mark, trace,” ling mâl “footprint,” probably related to mâlidan “to touch, rub; besmear;”
Mid.Pers. mâlih- “to be touched;” (Gurâni) mâl, mâlâ- Xunsâri mâl-/mâlâ “to smear, stroke.”

1a) A surviving mark, sign, or evidence of the former existence, influence, or action of some agent or event; vestige.

1b) A barely discernible indication or evidence of some quantity, quality, characteristic, expression, etc.

1c) An extremely small amount of some chemical component (Dictionary.com).

1d) Math.: → trace of a matrix.

2a) To follow the footprints, track, or traces of.

2b) To follow, make out, or determine the course or line of, especially by going backward from the latest evidence, nearest existence, etc. (Dictionary.com).

Etymology (EN): M.E. tracen, from M.Fr. tracier, from V.L. *tractiare “delineate, score, trace,” from L. tractus “track, course,” literally “a drawing out,” from p.p. stem of trahere “to pull, draw.”

Etymology (PE): Gilaki mâle “mark, trace, fingerprint; scar,” pâ mâle “footprint,” gaz mâle “bite mark;” Aftari mâl “trace, mark,” pae mâl “footprint,” ponjé mâl “mark of hand with fingers;” Tabari mâl “mark, trace,” ling mâl “footprint,” probably related to mâlidan “to touch, rub; besmear;”
Mid.Pers. mâlih- “to be touched;” (Gurâni) mâl, mâlâ- Xunsâri mâl-/mâlâ “to smear, stroke.”

Any → chemical element that is found in extremely small amounts, especially one used by organisms and held essential to maintain proper physical functioning.

See also: → trace; → element.

Any → chemical element that is found in extremely small amounts, especially one used by organisms and held essential to maintain proper physical functioning.

See also: → trace; → element.

Of a → square matrix, the → sum of the entries in the → main diagonal, i.e.: tr(A) = a₁₁ + a₂₂ + … + a_nn = Σ a_ii (i = 1 to n).

See also: → trace; → matrix.

Of a → square matrix, the → sum of the entries in the → main diagonal, i.e.: tr(A) = a₁₁ + a₂₂ + … + a_nn = Σ a_ii (i = 1 to n).

See also: → trace; → matrix.

A → substance, especially a → radioactive isotope, used in experiments
so that its movements through a biological, chemical, or physical system can be → monitored in order to study the → system.

See also: → trace, → -or.

A → substance, especially a → radioactive isotope, used in experiments
so that its movements through a biological, chemical, or physical system can be → monitored in order to study the → system.

See also: → trace, → -or.

The tube in humans and other air-breathing vertebrates extending from the larynx to the bronchi, serving as the principal passage for conveying air to and from the lungs; the windpipe (Dictionary.com).

Etymology (EN): M.E. trache, from M.L. trachea, from L.L. trachia, from Gk. trakheia, in trakheia arteria “windpipe.”

Etymology (PE): Nây, variants nay, ney, nâl “pipe, tube, reed, cane, windpipe;” Mid.Pers. nây “tube, reed, flute, clarion;” cf. Skt. nada-, nādha-, nala- “a hollow stalk, tube, pipe.”

The tube in humans and other air-breathing vertebrates extending from the larynx to the bronchi, serving as the principal passage for conveying air to and from the lungs; the windpipe (Dictionary.com).

Etymology (EN): M.E. trache, from M.L. trachea, from L.L. trachia, from Gk. trakheia, in trakheia arteria “windpipe.”

Etymology (PE): Nây, variants nay, ney, nâl “pipe, tube, reed, cane, windpipe;” Mid.Pers. nây “tube, reed, flute, clarion;” cf. Skt. nada-, nādha-, nala- “a hollow stalk, tube, pipe.”

1a) Evidence, as a mark or a series of marks, that something has passed.

1b) A path made or beaten by or as if by the feet of people or animals; trail (Dictionary.com).

1c) A line of motion, a course followed, such as
→ Hayashi track. See also:

→ evolutionary track, → Henyey track, → white dwarf cooling track, → tracking, → tracking accuracy.

2. To follow or pursue the track, traces, or footprints of.

Etymology (EN): M.E. trak, from M.Fr. trac, from O.Fr. trac “track of horses, trace” (mid-15c.), possibly from a Germanic source (compare M.L.G. treck, Du. trek “drawing, pulling).

Etymology (PE): Tor, from Lori, Laki, Fini, Bandar-Abâsi tor “track, trace, mark;” maybe ultimately from Proto-Ir. *tar- “to cross over;” cf. Av. tar- “to cross over;” Mid.Pers. (+*ui-) widur-, widôr- “to pass (beyond, over); Pers. gozar; Baluci tar(r)- “to walk;” Yaghnobi tir-, ter- “to go, leave;” → trans-.
Tor gereftan, with gereftan
“to take, seize” (Mid.Pers. griftan, Av./O.Pers. grab- “to take, seize,” cf.
Skt. grah-, grabh- “to seize, take,” graha “seizing, holding, perceiving,” M.L.G. grabben “to grab,” from P.Gmc. *grab, E. grab “to take or grasp suddenly;” PIE base *ghrebh- “to seize”).

1a) Evidence, as a mark or a series of marks, that something has passed.

1b) A path made or beaten by or as if by the feet of people or animals; trail (Dictionary.com).

1c) A line of motion, a course followed, such as
→ Hayashi track. See also:

→ evolutionary track, → Henyey track, → white dwarf cooling track, → tracking, → tracking accuracy.

2. To follow or pursue the track, traces, or footprints of.

Etymology (EN): M.E. trak, from M.Fr. trac, from O.Fr. trac “track of horses, trace” (mid-15c.), possibly from a Germanic source (compare M.L.G. treck, Du. trek “drawing, pulling).

Etymology (PE): Tor, from Lori, Laki, Fini, Bandar-Abâsi tor “track, trace, mark;” maybe ultimately from Proto-Ir. *tar- “to cross over;” cf. Av. tar- “to cross over;” Mid.Pers. (+*ui-) widur-, widôr- “to pass (beyond, over); Pers. gozar; Baluci tar(r)- “to walk;” Yaghnobi tir-, ter- “to go, leave;” → trans-.
Tor gereftan, with gereftan
“to take, seize” (Mid.Pers. griftan, Av./O.Pers. grab- “to take, seize,” cf.
Skt. grah-, grabh- “to seize, take,” graha “seizing, holding, perceiving,” M.L.G. grabben “to grab,” from P.Gmc. *grab, E. grab “to take or grasp suddenly;” PIE base *ghrebh- “to seize”).

The facility that allows a telescope to follow a celestial object during in its westward motion in the sky.

See also: Verbal noun from → track.

The facility that allows a telescope to follow a celestial object during in its westward motion in the sky.

See also: Verbal noun from → track.

The accuracy with which a → telescope tracks a target.

See also: → tracking; → accuracy

The accuracy with which a → telescope tracks a target.

See also: → tracking; → accuracy

An inherited or common body of beliefs or practices belonging to a particular people, family, or institution over a relatively long period. Also their transmission over time.

Etymology (EN): M.E. tradicion, from  O.Fr. tradicion, from L. traditionem “delivery, surrender, a handing down,” from traditus, p.p. of tradere “to deliver, hand over,” from → trans- “over” (time) + dare  “to give,” → datum.

Etymology (PE): Tarâdâd, from tarâ- “over time,” → trans-, + dâd past stem of dâdan “to give,” → datum.

An inherited or common body of beliefs or practices belonging to a particular people, family, or institution over a relatively long period. Also their transmission over time.

Etymology (EN): M.E. tradicion, from  O.Fr. tradicion, from L. traditionem “delivery, surrender, a handing down,” from traditus, p.p. of tradere “to deliver, hand over,” from → trans- “over” (time) + dare  “to give,” → datum.

Etymology (PE): Tarâdâd, from tarâ- “over time,” → trans-, + dâd past stem of dâdan “to give,” → datum.

The marks, signs, smells, etc., that are left behind by someone or something and that can often be followed (Webster). → star trail.

Etymology (EN): M.E. trailen “to draw or drag in the rear,” from O.Fr. trailler “to tow,” ultimately from L. tragula “dragnet,” probably related to trahere “to pull.”

Etymology (PE): Radd, variant of raj, râž, rak, râk, rezg (Lori), radé, râdé “line, rule, row,” rasté, râsté “row, a market with regular ranges of shops;” ris, risé “straight,” related to râst “right, true; just, upright, straight;” → system.

The marks, signs, smells, etc., that are left behind by someone or something and that can often be followed (Webster). → star trail.

Etymology (EN): M.E. trailen “to draw or drag in the rear,” from O.Fr. trailler “to tow,” ultimately from L. tragula “dragnet,” probably related to trahere “to pull.”

Etymology (PE): Radd, variant of raj, râž, rak, râk, rezg (Lori), radé, râdé “line, rule, row,” rasté, râsté “row, a market with regular ranges of shops;” ris, risé “straight,” related to râst “right, true; just, upright, straight;” → system.

1. A series or sequence of objects or events.
   

2. A line of coaches or wagons coupled together and drawn by a railway locomotive.

Etymology (EN): M.E., from O.Fr. train “tracks, path, trail; act of dragging,” from trainer “to pull, drag, draw,” from V.L. *traginare, from *tragere “to pull,” back-formation from tractus, p.p. of L. trahere “to pull, draw.”

Etymology (PE): Qatâr “a row of camels,” loan from Ar.; teran, loan from Fr., as above.

1. A series or sequence of objects or events.
   

2. A line of coaches or wagons coupled together and drawn by a railway locomotive.

Etymology (EN): M.E., from O.Fr. train “tracks, path, trail; act of dragging,” from trainer “to pull, drag, draw,” from V.L. *traginare, from *tragere “to pull,” back-formation from tractus, p.p. of L. trahere “to pull, draw.”

Etymology (PE): Qatâr “a row of camels,” loan from Ar.; teran, loan from Fr., as above.

Physics: The line or curve described by an object moving through space.
Math.: A curve or surface that cuts all of a given family of curves or surfaces at the same angle.

Etymology (EN): From Mod.L. trajectoria, from feminine of trajectorius “of or pertaining to throwing across,” from L. trajectus “thrown over or across,” p.p. of trajicere “throw across,” from L. → trans- “across” + icere, combining form of jacere “to throw,” → eject.

Etymology (PE): Tarâyešâné, from tarâ- “across,” → trans-,

• -y- epenthetic + ešân, present stem of ešândan, → eject, + relation suffix -é.

Physics: The line or curve described by an object moving through space.
Math.: A curve or surface that cuts all of a given family of curves or surfaces at the same angle.

Etymology (EN): From Mod.L. trajectoria, from feminine of trajectorius “of or pertaining to throwing across,” from L. trajectus “thrown over or across,” p.p. of trajicere “throw across,” from L. → trans- “across” + icere, combining form of jacere “to throw,” → eject.

Etymology (PE): Tarâyešâné, from tarâ- “across,” → trans-,

• -y- epenthetic + ešân, present stem of ešândan, → eject, + relation suffix -é.

Prefix meaning “across, beyond, through;” variant tra-; used with both space (point to point, shape to shape) and time (time to time, past to present, present to past) concepts.
See also:
→ tradition, → transauroral, → transcendental, → transdisciplinary, → transduce, → transfer, → transform, → transient, → transistor, → transit, → transition, → translate, → translucent, → translunar, → transmission, → transmit, → transmutate, → trans-Neptunian, → transonic, → transparent, → transponder, → transport, → transpose, → transversal, → transverse, → transuranium.

Etymology (EN): From L. trans-, from preposition trans “across, over, beyond,” cognate with Pers. tarâ- as below; cf. O.E. þurh, E. through; O.S. thuru; M.Du. dore, Du. door;
O.H.G. thuruh, Ger. durch; Goth. þairh “through;”
O.Ir. tre, Welsh tra “through;” PIE base *ter- “to cross.”

Etymology (PE): Tarâ-, from Mid.Pers. tar (preposition) “through, across, over, beyond; over time;” tarmenidan “to abuse, despise,” tarmenišn “conceited, disdainful;” O.Pers. tara “over, beyond, across;” Av. tarô, tarə “over, across, beyond,” from O.Pers./Av. tar- “to cross over,” O.Pers.
vi-tar- “to go across,” Mid.Pers. vitartan “to pass,” Mod.Pers. gozar, gozaštan “to pass, cross,” Av. tara-δāta- “placed beyond,” tarô-yāra- “outlasting the years” (over time), vī-tərəta- “taken away, isolated;” O.Pers. tara-draya- “overseas;” Sogdian tr- “to go;” cf. L. trans-, as above; Skt. tar- “to pass (through), overcome,” tárati “crosses, passes,” tirás “through, across, beyond.” The first element in the Mod.Pers. tarâvoš “exuding, trickling, oozing” is probably this prefix, → permeability. Another case may be tarzafân, tarzabân “interpreter, translator,” with zafân, zabân, → language.

Prefix meaning “across, beyond, through;” variant tra-; used with both space (point to point, shape to shape) and time (time to time, past to present, present to past) concepts.
See also:
→ tradition, → transauroral, → transcendental, → transdisciplinary, → transduce, → transfer, → transform, → transient, → transistor, → transit, → transition, → translate, → translucent, → translunar, → transmission, → transmit, → transmutate, → trans-Neptunian, → transonic, → transparent, → transponder, → transport, → transpose, → transversal, → transverse, → transuranium.

Etymology (EN): From L. trans-, from preposition trans “across, over, beyond,” cognate with Pers. tarâ- as below; cf. O.E. þurh, E. through; O.S. thuru; M.Du. dore, Du. door;
O.H.G. thuruh, Ger. durch; Goth. þairh “through;”
O.Ir. tre, Welsh tra “through;” PIE base *ter- “to cross.”

Etymology (PE): Tarâ-, from Mid.Pers. tar (preposition) “through, across, over, beyond; over time;” tarmenidan “to abuse, despise,” tarmenišn “conceited, disdainful;” O.Pers. tara “over, beyond, across;” Av. tarô, tarə “over, across, beyond,” from O.Pers./Av. tar- “to cross over,” O.Pers.
vi-tar- “to go across,” Mid.Pers. vitartan “to pass,” Mod.Pers. gozar, gozaštan “to pass, cross,” Av. tara-δāta- “placed beyond,” tarô-yāra- “outlasting the years” (over time), vī-tərəta- “taken away, isolated;” O.Pers. tara-draya- “overseas;” Sogdian tr- “to go;” cf. L. trans-, as above; Skt. tar- “to pass (through), overcome,” tárati “crosses, passes,” tirás “through, across, beyond.” The first element in the Mod.Pers. tarâvoš “exuding, trickling, oozing” is probably this prefix, → permeability. Another case may be tarzafân, tarzabân “interpreter, translator,” with zafân, zabân, → language.

A member of a class of objects in orbit around the Sun at a larger distance than the distance between Neptune and the Sun. This includes several → dwarf planets, such as → Eris, → Pluto, and many small solar system bodies.

See also: → trans-; → Neptune; → object.

A member of a class of objects in orbit around the Sun at a larger distance than the distance between Neptune and the Sun. This includes several → dwarf planets, such as → Eris, → Pluto, and many small solar system bodies.

See also: → trans-; → Neptune; → object.

A forbidden line emitted by interstellar ionized gas by several atomic species (O, O⁺, O⁺⁺, N⁺, S⁺⁺, etc.) corresponding to the transition from the electronic state 1S to 3P.
Examples are the ultraviolet line of the doubly ionized oxygen
[O III] at 2321 A and [N II] 3063 A. → auroral line;
→ forbidden line; → nebular line.

See also: → trans-; → auroral line.

A forbidden line emitted by interstellar ionized gas by several atomic species (O, O⁺, O⁺⁺, N⁺, S⁺⁺, etc.) corresponding to the transition from the electronic state 1S to 3P.
Examples are the ultraviolet line of the doubly ionized oxygen
[O III] at 2321 A and [N II] 3063 A. → auroral line;
→ forbidden line; → nebular line.

See also: → trans-; → auroral line.

1. General: Surpassing or superior.
   
2. Math.: → transcendental function, → transcendental number.

Etymology (EN): From transcendentalis, from transcendere “to climb over or beyond, surmount,” from → trans- “beyond” + scandere “to climb” + -alis, → -al.

Etymology (PE): Tarâfarâzandé, from tarâ- “beyond, over,” → trans-,

• farâzandé agent noun of farâzandan “to raise, erect, exalt,” from farâz “above, up, upon, on the top, aloft,” from Mid.Pers. farâz, farâc “forward, prominent, distinguished;” Av. frānk- (adj.) “turned toward the front,” fraca (adv.) “forward, forth,” fraš (adv.) “forward, forth; before;” Proto-Iranian *frānk-.

1. General: Surpassing or superior.
   
2. Math.: → transcendental function, → transcendental number.

Etymology (EN): From transcendentalis, from transcendere “to climb over or beyond, surmount,” from → trans- “beyond” + scandere “to climb” + -alis, → -al.

Etymology (PE): Tarâfarâzandé, from tarâ- “beyond, over,” → trans-,

• farâzandé agent noun of farâzandan “to raise, erect, exalt,” from farâz “above, up, upon, on the top, aloft,” from Mid.Pers. farâz, farâc “forward, prominent, distinguished;” Av. frānk- (adj.) “turned toward the front,” fraca (adv.) “forward, forth,” fraš (adv.) “forward, forth; before;” Proto-Iranian *frānk-.

A function which is not → algebraic. For example y = cosx, y = 10^xx.

See also: → transcendental; → function.

A function which is not → algebraic. For example y = cosx, y = 10^xx.

See also: → transcendental; → function.

In Kantian epistemology, a pure logic which contains solely the rules of the pure thought of an object, excluding any mode of knowledge with empirical content.
Whereas general logic is not concerned with the origin of our cognitions, transcendental logic would contain rules for the use of → a priori cognitions.

See also: → transcendental; → logic.

In Kantian epistemology, a pure logic which contains solely the rules of the pure thought of an object, excluding any mode of knowledge with empirical content.
Whereas general logic is not concerned with the origin of our cognitions, transcendental logic would contain rules for the use of → a priori cognitions.

See also: → transcendental; → logic.

A → real number that is not a → root of any → algebraic equation with → rational → coefficients. Every transcendental number is → irrational. Examples of transcendental numbers are
π = 3.1415926… and e = 2.7182818…

See also: → transcendental; → number.

A → real number that is not a → root of any → algebraic equation with → rational → coefficients. Every transcendental number is → irrational. Examples of transcendental numbers are
π = 3.1415926… and e = 2.7182818…

See also: → transcendental; → number.

Of a comprehensive framework that transcends the partial scope of disciplinary worldviews through an overarching synthesis, such as general systems, feminist theory, and sustainability. The term also connotes a new structure of unity informed by the worldview of complexity in science and a new mode of knowledge production that draws on expertise from a wider range of organizations, and collaborations with stakeholders in society. See also → interdisciplinary and
→ multidisciplinary
(Thompson Klein, J. 2010, Creating Interdisciplinary Campus Culture, John Wiley and Sons, Inc.).

See also: → trans-; → disciplinary.

Of a comprehensive framework that transcends the partial scope of disciplinary worldviews through an overarching synthesis, such as general systems, feminist theory, and sustainability. The term also connotes a new structure of unity informed by the worldview of complexity in science and a new mode of knowledge production that draws on expertise from a wider range of organizations, and collaborations with stakeholders in society. See also → interdisciplinary and
→ multidisciplinary
(Thompson Klein, J. 2010, Creating Interdisciplinary Campus Culture, John Wiley and Sons, Inc.).

See also: → trans-; → disciplinary.

To convert (energy) from one form into another.

Etymology (EN): From L. transducere “lead across, transfer,” from → trans- “across” + ducere “to lead.”

Etymology (PE): Tarâhâxtan, from tarâ-, → trans-, + hâxtan, hâzidan, from Mid.Pers. “to lead, guide, persuade,” Av. hak-, hacaiti “to attach oneself to, to join,” cf. Skt. sacate “accompanies, follows,” Gk. hepesthai “to follow,", L. sequi “to follow;” PIE *sekw-.

To convert (energy) from one form into another.

Etymology (EN): From L. transducere “lead across, transfer,” from → trans- “across” + ducere “to lead.”

Etymology (PE): Tarâhâxtan, from tarâ-, → trans-, + hâxtan, hâzidan, from Mid.Pers. “to lead, guide, persuade,” Av. hak-, hacaiti “to attach oneself to, to join,” cf. Skt. sacate “accompanies, follows,” Gk. hepesthai “to follow,", L. sequi “to follow;” PIE *sekw-.

A device that converts one type of energy to another for various purposes, such as a microphone that converts acoustic energy into electrical impulses or a photodetector that converts modulated light waves to electrical currents.

See also: Agent noun of → transduce.

A device that converts one type of energy to another for various purposes, such as a microphone that converts acoustic energy into electrical impulses or a photodetector that converts modulated light waves to electrical currents.

See also: Agent noun of → transduce.

1. The conveying of something or energy from one place or position to another.
   → charge-transfer device; → energy transfer; → heat transfer; → optical transfer function; → radiative transfer; → radiative transfer equation.
   

2a) To convey or pass from one place to another.

2b) To copy information or images from one place or object to another.

Etymology (EN): M.E. transferren (v.), from L. transferre “to carry over, transfer, translate,” from → trans- “across” + ferre “to carry;” cognate with Pers. bordan “to carry, transport;” Mid.Pers. burdan;
O.Pers./Av. bar- “to bear, carry,” barəθre “to bear (infinitive);” Skt. bharati “he carries;” Gk. pherein “to carry;” PIE base *bher- “to carry.”

Etymology (PE): Tarâvaž, from tarâ-, → trans- “across,” + važ, variant vâz (in parvâz), Av.
vaz- “to draw, guide; bring; possess; fly; float,” vazaiti “guides, leads”
(cf. Skt. vah- “to carry, drive, convey,” vahati “carries,”
pravaha- “bearing along, carrying,” pravāha- “running water, stream, river;” L. vehere “to carry;” O.E. wegan “to carry;” O.N. vegr; O.H.G. weg “way,” wegan “to move,” wagan “cart;” M.Du. wagen “wagon;” PIE base *wegh- “to drive;” see also → flight).

1. The conveying of something or energy from one place or position to another.
   → charge-transfer device; → energy transfer; → heat transfer; → optical transfer function; → radiative transfer; → radiative transfer equation.
   

2a) To convey or pass from one place to another.

2b) To copy information or images from one place or object to another.

Etymology (EN): M.E. transferren (v.), from L. transferre “to carry over, transfer, translate,” from → trans- “across” + ferre “to carry;” cognate with Pers. bordan “to carry, transport;” Mid.Pers. burdan;
O.Pers./Av. bar- “to bear, carry,” barəθre “to bear (infinitive);” Skt. bharati “he carries;” Gk. pherein “to carry;” PIE base *bher- “to carry.”

Etymology (PE): Tarâvaž, from tarâ-, → trans- “across,” + važ, variant vâz (in parvâz), Av.
vaz- “to draw, guide; bring; possess; fly; float,” vazaiti “guides, leads”
(cf. Skt. vah- “to carry, drive, convey,” vahati “carries,”
pravaha- “bearing along, carrying,” pravāha- “running water, stream, river;” L. vehere “to carry;” O.E. wegan “to carry;” O.N. vegr; O.H.G. weg “way,” wegan “to move,” wagan “cart;” M.Du. wagen “wagon;” PIE base *wegh- “to drive;” see also → flight).

The mathematical relationship between the output of a control system and its input: for a linear system, it is the Laplace transform of the output divided by the Laplace transform of the input under conditions of zero initial-energy storage.

See also: → transfer; → function.

The mathematical relationship between the output of a control system and its input: for a linear system, it is the Laplace transform of the output divided by the Laplace transform of the input under conditions of zero initial-energy storage.

See also: → transfer; → function.

1. Math.: A mathematical quantity obtained from a given quantity by an algebraic, geometric, or functional transformation.
   The transformation itself.
   

2. To change in form, appearance, or structure; to change in condition, nature, or character; convert.
   Physics: To change into another form of energy.
   

To increase or decrease (the voltage and current characteristics of an alternating-current circuit), as by means of a transformer.
Math.: To change the form of (a figure, expression, etc.) without in general changing the value.

See also: → trans- + → form.

1. Math.: A mathematical quantity obtained from a given quantity by an algebraic, geometric, or functional transformation.
   The transformation itself.
   

2. To change in form, appearance, or structure; to change in condition, nature, or character; convert.
   Physics: To change into another form of energy.
   

To increase or decrease (the voltage and current characteristics of an alternating-current circuit), as by means of a transformer.
Math.: To change the form of (a figure, expression, etc.) without in general changing the value.

See also: → trans- + → form.

1. The act or process of transforming. The state of being transformed.
   

2. The relationship between description of a physical phenomenon in one → reference frame to another. → Galilean transformation; → Lorentz transformation.
   

3. Math.: The act, process, or result of transforming or mapping.

See also: Verbal noun of → transform.

1. The act or process of transforming. The state of being transformed.
   

2. The relationship between description of a physical phenomenon in one → reference frame to another. → Galilean transformation; → Lorentz transformation.
   

3. Math.: The act, process, or result of transforming or mapping.

See also: Verbal noun of → transform.

A device that converts low voltages to higher voltages, or vice versa. A transformer consists of a primary coil and a secondary coil, both traversed by the same magnetic flux.

See also: → transform + → -or.

A device that converts low voltages to higher voltages, or vice versa. A transformer consists of a primary coil and a secondary coil, both traversed by the same magnetic flux.

See also: → transform + → -or.

General: Lasting for only a short time; not permanent.
Physics: A non-periodic signal of short duration. A sudden pulse of voltage or current.

Etymology (EN): From L. transiens “passing over or away,” pr.p. of L. transire “to go or cross over,” from → trans- “cross” + ire “to go.”

Etymology (PE): Gozarâ “transient,” from gozar present stem of gozaštan “to pass, cross, transit,” variant gozâštan “to put, to place, let, allow;” Mid.Pers. widardan, widâštan “to pass, to let pass (by);” O.Pers. vitar- “to pass across,” viyatarayam “I put across;” Av. vi-tar- “to pass across,” from vi- “apart, away from” (O.Pers. viy- “apart, away;” Av. vi- “apart, away;” cf. Skt. vi- “apart, asunder, away, out;” L. vitare “to avoid, turn aside”) + O.Pers./Av. tar- “to cross over;” → trans-.

General: Lasting for only a short time; not permanent.
Physics: A non-periodic signal of short duration. A sudden pulse of voltage or current.

Etymology (EN): From L. transiens “passing over or away,” pr.p. of L. transire “to go or cross over,” from → trans- “cross” + ire “to go.”

Etymology (PE): Gozarâ “transient,” from gozar present stem of gozaštan “to pass, cross, transit,” variant gozâštan “to put, to place, let, allow;” Mid.Pers. widardan, widâštan “to pass, to let pass (by);” O.Pers. vitar- “to pass across,” viyatarayam “I put across;” Av. vi-tar- “to pass across,” from vi- “apart, away from” (O.Pers. viy- “apart, away;” Av. vi- “apart, away;” cf. Skt. vi- “apart, asunder, away, out;” L. vitare “to avoid, turn aside”) + O.Pers./Av. tar- “to cross over;” → trans-.

A short-lived change in the brightness of patches on the face of the Moon. The TLPs last from a few seconds to a few hours and can grow from less than a few to a hundred kilometers in size. They have been reported by many observers since the invention of the telescope. However, the physical mechanism responsible for creating a TLP is not well understood. Several theories have been proposed, among which lunar outgassing, that is, gas being released from the surface of the Moon.

See also: → transient; → lunar;
→ phenomenon.

A short-lived change in the brightness of patches on the face of the Moon. The TLPs last from a few seconds to a few hours and can grow from less than a few to a hundred kilometers in size. They have been reported by many observers since the invention of the telescope. However, the physical mechanism responsible for creating a TLP is not well understood. Several theories have been proposed, among which lunar outgassing, that is, gas being released from the surface of the Moon.

See also: → transient; → lunar;
→ phenomenon.

A general term for all events of astronomical nature occurring in the sky and lasting only for a relatively short duration, such as → supernova explosions, → gamma-ray bursts, → flare stars, → luminous red novae, eclipsing brown dwarfs, → tidal disruption events, etc.

See also: → transient; → sky.

A general term for all events of astronomical nature occurring in the sky and lasting only for a relatively short duration, such as → supernova explosions, → gamma-ray bursts, → flare stars, → luminous red novae, eclipsing brown dwarfs, → tidal disruption events, etc.

See also: → transient; → sky.

An X-ray source that appears suddenly in the sky, strongly increases its intensity over a few days, and then declines with a lifetime of several months.

See also: → transient; → X-ray source.

An X-ray source that appears suddenly in the sky, strongly increases its intensity over a few days, and then declines with a lifetime of several months.

See also: → transient; → X-ray source.

An active semiconductor device with a small low-powered solid-state electronic device consisting of a semiconductor and three or more electrodes, used as an amplifier and rectifier and frequently incorporated into integrated circuit chips. Although much smaller in size than a vacuum tube, it performs similar functions without requiring current to heat a cathode.

See also: From trans-, from → transfer + -istor, from → resistor; → resistance.

An active semiconductor device with a small low-powered solid-state electronic device consisting of a semiconductor and three or more electrodes, used as an amplifier and rectifier and frequently incorporated into integrated circuit chips. Although much smaller in size than a vacuum tube, it performs similar functions without requiring current to heat a cathode.

See also: From trans-, from → transfer + -istor, from → resistor; → resistance.

1. An event where one astronomical object appears to move across the face of another. As seen from Earth, the planets Venus and Mercury are seen to transit the Sun. We can also observe natural satellites transit the face of their host planet. Similarly exoplanets have been observed to transit their host stars. See also → planetary transit, → transit method.
   

2. The passage of a heavenly body across the meridian of a given location.

Etymology (EN): M.E., from L. transitus, p.p. of transire “to go or cross over,” from → trans- “across” + ire “to go.”

Etymology (PE): Gozar “passage, transit, passing,” from gozaštan “to pass, cross, transit,” variant gozâštan “to put, to place, let, allow;” Mid.Pers. widardan, widâštan “to pass, to let pass (by);” O.Pers. vitar- “to pass across,” viyatarayam “I put across;” Av. vi-tar- “to pass across,” from vi- “apart, away from” (O.Pers. viy- “apart, away;” Av. vi- “apart, away;” cf. Skt. vi- “apart, asunder, away, out;” L. vitare “to avoid, turn aside”) + O.Pers./Av. tar- “to cross over;” → trans-.

1. An event where one astronomical object appears to move across the face of another. As seen from Earth, the planets Venus and Mercury are seen to transit the Sun. We can also observe natural satellites transit the face of their host planet. Similarly exoplanets have been observed to transit their host stars. See also → planetary transit, → transit method.
   

2. The passage of a heavenly body across the meridian of a given location.

Etymology (EN): M.E., from L. transitus, p.p. of transire “to go or cross over,” from → trans- “across” + ire “to go.”

Etymology (PE): Gozar “passage, transit, passing,” from gozaštan “to pass, cross, transit,” variant gozâštan “to put, to place, let, allow;” Mid.Pers. widardan, widâštan “to pass, to let pass (by);” O.Pers. vitar- “to pass across,” viyatarayam “I put across;” Av. vi-tar- “to pass across,” from vi- “apart, away from” (O.Pers. viy- “apart, away;” Av. vi- “apart, away;” cf. Skt. vi- “apart, asunder, away, out;” L. vitare “to avoid, turn aside”) + O.Pers./Av. tar- “to cross over;” → trans-.

An observing instrument provided with a graduated vertical scale, used to measure the declinations of heavenly bodies and to determine the time of meridian transits. Same as → meridian circle.

See also: → transit; → circle; nimruzâni, adj. of nimruzân, → meridian.

An observing instrument provided with a graduated vertical scale, used to measure the declinations of heavenly bodies and to determine the time of meridian transits. Same as → meridian circle.

See also: → transit; → circle; nimruzâni, adj. of nimruzân, → meridian.

An instrument mounted so as to allow it to be pointed only at objects in the sky crossing the local meridian. Also known as → transit telescope.

See also: → transit; → instrument.

An instrument mounted so as to allow it to be pointed only at objects in the sky crossing the local meridian. Also known as → transit telescope.

See also: → transit; → instrument.

A method for detecting → exoplanets that is based on the decrease of star → brightness when the exoplanet passes in front of its star. As the planet transits, a portion of the light from the star is blocked causing a decrease in the → magnitude of the star. The amount of decrease (typically between 0.01% and 1%) depends on the sizes of the star and the planet. The duration of the transit depends on the planet’s distance from the star and the star’s mass. This change must be periodic if it is caused by a planet. In addition, all transits produced by the same planet must be of the same change in brightness and last the same amount of time. Once detected, the planet’s distance from its star can be calculated from the period and the mass of the star using → Kepler’s third law of planetary motion. The size of the planet is found from the depth of the transit and the size of the star. From the orbital size and the temperature of the star, the planet’s characteristic temperature can be calculated. Knowing the star’s mass and size, the planet’s size and distance can be estimated. Also the composition of a → transiting planet’s atmosphere can, in principle, be determined.

See also: → transit; → method.

A method for detecting → exoplanets that is based on the decrease of star → brightness when the exoplanet passes in front of its star. As the planet transits, a portion of the light from the star is blocked causing a decrease in the → magnitude of the star. The amount of decrease (typically between 0.01% and 1%) depends on the sizes of the star and the planet. The duration of the transit depends on the planet’s distance from the star and the star’s mass. This change must be periodic if it is caused by a planet. In addition, all transits produced by the same planet must be of the same change in brightness and last the same amount of time. Once detected, the planet’s distance from its star can be calculated from the period and the mass of the star using → Kepler’s third law of planetary motion. The size of the planet is found from the depth of the transit and the size of the star. From the orbital size and the temperature of the star, the planet’s characteristic temperature can be calculated. Knowing the star’s mass and size, the planet’s size and distance can be estimated. Also the composition of a → transiting planet’s atmosphere can, in principle, be determined.

See also: → transit; → method.

The crossing the face of the Sun by the planet Mercury, as seen from Earth. Because the plane of Mercury’s orbit is not exactly coincident with the plane of Earth’s orbit, Mercury usually appears to pass over or under the Sun. On the average it occurs 13 times each century when the Earth is near the → line of nodes of Mercury’s orbit. The three last transits were on 2003 May 07, 2006 November 08, and 2016 May 09. The next one will be on 2019 November 11. The first observation of a transit of Mercury was on November 7, 1631 by Pierre Gassendi. On June 4, 2014 NASA’s Mars rover Curiosity photographed a transit of Mercury, marking the first time such a phenomenon has ever been imaged from the surface of a planet other than Earth. See also → black drop.

See also: → Mercury; → transit.

The crossing the face of the Sun by the planet Mercury, as seen from Earth. Because the plane of Mercury’s orbit is not exactly coincident with the plane of Earth’s orbit, Mercury usually appears to pass over or under the Sun. On the average it occurs 13 times each century when the Earth is near the → line of nodes of Mercury’s orbit. The three last transits were on 2003 May 07, 2006 November 08, and 2016 May 09. The next one will be on 2019 November 11. The first observation of a transit of Mercury was on November 7, 1631 by Pierre Gassendi. On June 4, 2014 NASA’s Mars rover Curiosity photographed a transit of Mercury, marking the first time such a phenomenon has ever been imaged from the surface of a planet other than Earth. See also → black drop.

See also: → Mercury; → transit.

A rare phenomenon that happens when the planet Venus passes directly between the Sun and Earth and is therefore seen against the solar disk. Such a passage occurs every 122 or 105 years and when it happens the next occurrence is after 8 years. Only seven transits of Venus have occurred since the invention of the telescope:
in 1639, 1761, 1769, 1874, 1882, 2004, and 2012. The next one will be in 2117.
The reason for this rarity is that the Earth and Venus do not orbit the Sun in the same plane. Their orbital planes have a relative inclination of about 3°. The first observation of the Venus transit was in 1639 by the English Jeremiah Horrocks (1618-1641). See also → black drop.

See also: → Venus; → transit

A rare phenomenon that happens when the planet Venus passes directly between the Sun and Earth and is therefore seen against the solar disk. Such a passage occurs every 122 or 105 years and when it happens the next occurrence is after 8 years. Only seven transits of Venus have occurred since the invention of the telescope:
in 1639, 1761, 1769, 1874, 1882, 2004, and 2012. The next one will be in 2117.
The reason for this rarity is that the Earth and Venus do not orbit the Sun in the same plane. Their orbital planes have a relative inclination of about 3°. The first observation of the Venus transit was in 1639 by the English Jeremiah Horrocks (1618-1641). See also → black drop.

See also: → Venus; → transit

Same as → transit instrument.

See also: → transit; → telescope.

Same as → transit instrument.

See also: → transit; → telescope.

The time interval between the release of an electron at the photocathode and the arrival of an electron at the anode. Transit time is not a single-valued quantity, but has a bell-shaped distribution.

See also: → transit; → time.

The time interval between the release of an electron at the photocathode and the arrival of an electron at the anode. Transit time is not a single-valued quantity, but has a bell-shaped distribution.

See also: → transit; → time.

A → NASA space telescope devoted to the hunt for planets orbiting the brightest stars in the sky, launched on April 18, 2018. The mission is planned to monitor at least 200,000 stars for signs of → exoplanets using the → planetary transit method.

TESS is equipped with four identical refractive → cameras with a combined → field of view (FOV) of 24 × 96 degrees. Each camera consists of a → CCD detector assembly, a → lens assembly, and a lens hood. The → entrance pupil diameter is 10.5 cm and the wavelength range 600 to 1,000 nm.

The satellite is a follow-up of NASA’s → Kepler spacecraft, but focuses on stars that are 30 to 100 times brighter than those Kepler examined.

See also: → transit; → exoplanet; → survey.

A → NASA space telescope devoted to the hunt for planets orbiting the brightest stars in the sky, launched on April 18, 2018. The mission is planned to monitor at least 200,000 stars for signs of → exoplanets using the → planetary transit method.

TESS is equipped with four identical refractive → cameras with a combined → field of view (FOV) of 24 × 96 degrees. Each camera consists of a → CCD detector assembly, a → lens assembly, and a lens hood. The → entrance pupil diameter is 10.5 cm and the wavelength range 600 to 1,000 nm.

The satellite is a follow-up of NASA’s → Kepler spacecraft, but focuses on stars that are 30 to 100 times brighter than those Kepler examined.

See also: → transit; → exoplanet; → survey.

A planet that passes in front of its star directly between Earth and the star. The → transit method is used for detecting → exoplanets around stars.

See also: → transit; → planet.

A planet that passes in front of its star directly between Earth and the star. The → transit method is used for detecting → exoplanets around stars.

See also: → transit; → planet.

A Belgian facility devoted to the detection and characterization of → exoplanets and to the study of → comets (→ transiting planet) and other → small solar system bodies. It consists of two 60 cm robotic telescopes located at the → European Southern Observatory, → La Silla, in Chile and at Oukaïmden Observatory in Marroco.

See also: → transit; → planet; → planetesimal; → small; → telescope.

A Belgian facility devoted to the detection and characterization of → exoplanets and to the study of → comets (→ transiting planet) and other → small solar system bodies. It consists of two 60 cm robotic telescopes located at the → European Southern Observatory, → La Silla, in Chile and at Oukaïmden Observatory in Marroco.

See also: → transit; → planet; → planetesimal; → small; → telescope.

1. Passage from one position, state, stage, subject, concept, etc., to another.
   

2. A change between phases such as solid to liquid or liquid to gas.
   

3. A change in the → energy level or state of an atom or nucleus. → atomic transition, → bound-bound transition, → bound-free transition, → cascade transition, → discrete transition, → forbidden transition, → hyperfine transition, → nuclear transition, → permitted transition, → phase transition, → quark-hadron phase transition, → radiative transition, → rotational transition, → semi-forbidden transition, → transition disk, → transition function, → transition probability, → vibrational transition.

Etymology (EN): From L. transitionem (nominative transition) “a going across or over,” noun of action from transire “go or cross over,” from → trans- “across” + ire “to go.”

Etymology (PE): Gozareš, verbal noun of gozaštan “to transit, pass,” → transit, + -eš, → -tion.

1. Passage from one position, state, stage, subject, concept, etc., to another.
   

2. A change between phases such as solid to liquid or liquid to gas.
   

3. A change in the → energy level or state of an atom or nucleus. → atomic transition, → bound-bound transition, → bound-free transition, → cascade transition, → discrete transition, → forbidden transition, → hyperfine transition, → nuclear transition, → permitted transition, → phase transition, → quark-hadron phase transition, → radiative transition, → rotational transition, → semi-forbidden transition, → transition disk, → transition function, → transition probability, → vibrational transition.

Etymology (EN): From L. transitionem (nominative transition) “a going across or over,” noun of action from transire “go or cross over,” from → trans- “across” + ire “to go.”

Etymology (PE): Gozareš, verbal noun of gozaštan “to transit, pass,” → transit, + -eš, → -tion.

The → accretion disk of a → T Tauri star that displays very weak or no → infrared excess at → near infrared wavelengths, but shows strong excess at → intermediate infrared and longer wavelengths.
This happens when the hot inner dust disk has dissipated whereas the cooler outer disk is still intact.

See also: → transition; → disk.

The → accretion disk of a → T Tauri star that displays very weak or no → infrared excess at → near infrared wavelengths, but shows strong excess at → intermediate infrared and longer wavelengths.
This happens when the hot inner dust disk has dissipated whereas the cooler outer disk is still intact.

See also: → transition; → disk.

The → probability of finding the → Universe in a → state labelled X₂ at a time t₂, if it was in a state X₁ at an earlier time t₁.

See also: → transition; → function.

The → probability of finding the → Universe in a → state labelled X₂ at a time t₂, if it was in a state X₁ at an earlier time t₁.

See also: → transition; → function.

The probability that a quantum-mechanical system will make a transition from a given initial state to a given final state.

See also: → transition; → probability.

The probability that a quantum-mechanical system will make a transition from a given initial state to a given final state.

See also: → transition; → probability.

In fluid mechanics, a flow composed of → laminar and → turbulent flows, for which the → Reynolds number is between 2300 and 4000.

See also: → transition; → flow.

In fluid mechanics, a flow composed of → laminar and → turbulent flows, for which the → Reynolds number is between 2300 and 4000.

See also: → transition; → flow.

1a) Mechanics: To subject a body to → translation.

1b) Math.: To perform a → translation.

2a) To turn from one language into another.

2b) To convert computer data to a different form according to an → algorithm.

Etymology (EN): M.E. translaten, from L. translatus, from → trans- “across” + latus suppletive p.p. of ferre “to carry;” cognate with Pers. bordan “to carry, transport;” Mid.Pers. burdan;
O.Pers./Av. bar- “to bear, carry,” barəθre “to bear (infinitive);” Skt. bharati “he carries;” Gk. pherein “to carry;” PIE base *bher- “to carry.”

Etymology (PE): 1) Tarâjâyidan, from tarâ-, → trans- “across” + jâ “place” (from Mid.Pers. giyag “place;” O.Pers. ā-vahana- “place, village;” Av. vah- “to dwell, stay,” vanhaiti “he dwells, stays;” Skt. vásati “he dwells;” Gk. aesa (nukta) “to pass (the night);”
Ossetic wat “room; bed; place;” Tokharian B wäs- “to stay, wait;” PIE base *ues- “to stay, live, spend the night”)

• -idan infinitive suffix.
  

2. Tarâzabânidan, from tarâ-, as above, +
   zabân “tongue; language” (Mid.Pers. uzwân “tongue; language;” O.Pers. hzanm, hizānam “tongue;” Av. hizuua-, hizū- “tongue;” cf. Skt. jivhā- “tongue;” L. lingua “tongue, speech, language;” O.Ir. tenge; Welsh tafod; Lith. liezuvis; O.C.S. jezyku; M.Du. tonghe; Du. tong; O.H.G. zunga; Ger. Zunge; Goth. tuggo; PIE base *dnghwa-) + -idan infinitive suffix. The similarity of tarâzabân with the classical Pers. terms tarzafân, tarzabân “a person who translates orally from one language into another; eloquent” is intriguing: from tar- variant of tarâ-

• zafân, zabân “tongue, language”?!

1a) Mechanics: To subject a body to → translation.

1b) Math.: To perform a → translation.

2a) To turn from one language into another.

2b) To convert computer data to a different form according to an → algorithm.

Etymology (EN): M.E. translaten, from L. translatus, from → trans- “across” + latus suppletive p.p. of ferre “to carry;” cognate with Pers. bordan “to carry, transport;” Mid.Pers. burdan;
O.Pers./Av. bar- “to bear, carry,” barəθre “to bear (infinitive);” Skt. bharati “he carries;” Gk. pherein “to carry;” PIE base *bher- “to carry.”

Etymology (PE): 1) Tarâjâyidan, from tarâ-, → trans- “across” + jâ “place” (from Mid.Pers. giyag “place;” O.Pers. ā-vahana- “place, village;” Av. vah- “to dwell, stay,” vanhaiti “he dwells, stays;” Skt. vásati “he dwells;” Gk. aesa (nukta) “to pass (the night);”
Ossetic wat “room; bed; place;” Tokharian B wäs- “to stay, wait;” PIE base *ues- “to stay, live, spend the night”)

• -idan infinitive suffix.
  

2. Tarâzabânidan, from tarâ-, as above, +
   zabân “tongue; language” (Mid.Pers. uzwân “tongue; language;” O.Pers. hzanm, hizānam “tongue;” Av. hizuua-, hizū- “tongue;” cf. Skt. jivhā- “tongue;” L. lingua “tongue, speech, language;” O.Ir. tenge; Welsh tafod; Lith. liezuvis; O.C.S. jezyku; M.Du. tonghe; Du. tong; O.H.G. zunga; Ger. Zunge; Goth. tuggo; PIE base *dnghwa-) + -idan infinitive suffix. The similarity of tarâzabân with the classical Pers. terms tarzafân, tarzabân “a person who translates orally from one language into another; eloquent” is intriguing: from tar- variant of tarâ-

• zafân, zabân “tongue, language”?!

1. Mechanics: A motion of a rigid body characterized by parallel paths of all particles. Every point of the body in translation has the same velocity and acceleration at any particular instant. The translation motion may be rectilinear or curvilinear.
   

2. Math.: A transformation which moves all points on a plane through the same distance in the same direction. The object and its image are congruent. Also a function obtained from a given function by adding the same constant to the value of each of its variables.
   

3. A rendering from one language into another; a version of such a rendering.

Etymology (EN): Verbal noun of → translate.

Etymology (PE): Tarâjâyeš, verbal noun of tarâjâyidan, tarâzabâneš, verbal noun of tarâzabânidan, → translate.

1. Mechanics: A motion of a rigid body characterized by parallel paths of all particles. Every point of the body in translation has the same velocity and acceleration at any particular instant. The translation motion may be rectilinear or curvilinear.
   

2. Math.: A transformation which moves all points on a plane through the same distance in the same direction. The object and its image are congruent. Also a function obtained from a given function by adding the same constant to the value of each of its variables.
   

3. A rendering from one language into another; a version of such a rendering.

Etymology (EN): Verbal noun of → translate.

Etymology (PE): Tarâjâyeš, verbal noun of tarâjâyidan, tarâzabâneš, verbal noun of tarâzabânidan, → translate.

The quality of a material that allows light to pass through, but only diffusely, so that objects on the other side cannot be clearly distinguished. → transparent.

Etymology (EN): From L. translucent-, p.p. of translucere “to shine through,” from → trans- + lucere “to shine,” related to lux “light,” lucidus “clear,” luna, “moon;” Fr. lumière “light;” cf. Pers. ruz “day,” rowšan “bright, clear,” rowzan “window, aperture;” foruq “light,”
afruxtan “to light, kindle;”
Mid.Pers. rôšn “light; bright, luminous,” rôc “day;” O.Pers. raucah-rocânak “window;” O.Pers. raocah- “light, luminous; daylight;”
Av. raocana- “bright, shining, radiant;” akin to Skt. rocaná- “bright, shining,” roka- “brightness, light;” Gk. leukos “white, clear;” O.E. leoht, leht, from W.Gmc. *leukhtam (cf. O.Fris. liacht, M.Du. lucht, Ger. Licht), from PIE *leuk- “light, brightness.”

Etymology (PE): Tarâtâb, from tarâ-, → trans- + tâb present stem of tâbidan “to shine,” variants tâftan “to shine,” tafsidan “to become hot;” Mid.Pers. tâftan “to heat, burn, shine;” taftan “to become hot;” Parthian t’b “to shine;”
Av. tāp-, taf- “to warm up, heat,” tafsat “became hot,” tāpaiieiti “to create warmth;” cf. Skt. tap- “to heat, be/become hot; to spoil, injure, damage; to suffer,”
tapati “burns;” L. tepere “to be warm,” tepidus “warm;” PIE base *tep- “to be warm.”

The quality of a material that allows light to pass through, but only diffusely, so that objects on the other side cannot be clearly distinguished. → transparent.

Etymology (EN): From L. translucent-, p.p. of translucere “to shine through,” from → trans- + lucere “to shine,” related to lux “light,” lucidus “clear,” luna, “moon;” Fr. lumière “light;” cf. Pers. ruz “day,” rowšan “bright, clear,” rowzan “window, aperture;” foruq “light,”
afruxtan “to light, kindle;”
Mid.Pers. rôšn “light; bright, luminous,” rôc “day;” O.Pers. raucah-rocânak “window;” O.Pers. raocah- “light, luminous; daylight;”
Av. raocana- “bright, shining, radiant;” akin to Skt. rocaná- “bright, shining,” roka- “brightness, light;” Gk. leukos “white, clear;” O.E. leoht, leht, from W.Gmc. *leukhtam (cf. O.Fris. liacht, M.Du. lucht, Ger. Licht), from PIE *leuk- “light, brightness.”

Etymology (PE): Tarâtâb, from tarâ-, → trans- + tâb present stem of tâbidan “to shine,” variants tâftan “to shine,” tafsidan “to become hot;” Mid.Pers. tâftan “to heat, burn, shine;” taftan “to become hot;” Parthian t’b “to shine;”
Av. tāp-, taf- “to warm up, heat,” tafsat “became hot,” tāpaiieiti “to create warmth;” cf. Skt. tap- “to heat, be/become hot; to spoil, injure, damage; to suffer,”
tapati “burns;” L. tepere “to be warm,” tepidus “warm;” PIE base *tep- “to be warm.”

A type of → interstellar medium cloud where → carbon (C), in → ionized atomic form and protected from → interstellar radiation, transforms into neutral atomic or molecular form. The chemistry in this regime is qualitatively different than in the → diffuse molecular clouds, both because of the decreasing electron fraction and because of the abundance of the highly reactive C atoms.

The translucent cloud regime is the least well understood of all the cloud types. This is partly because of a relative lack of observational data, but also because theoretical models do not all agree on the chemical behavior in this transition region. In some models, there is a zone where the abundance of C exceeds that of C⁺ and CO; in others the peak abundance of C falls below that of C+ and CO. To cope with this uncertainty, Snow & McCall (2006) propose a working definition of translucent cloud material as gas with C⁺ fraction < 0.5 and CO fraction < 0.9. This definition reflects the fact that C+ is no longer the dominant form of carbon as it converts to neutral or molecular form, but also excludes the → dense molecular clouds, where carbon is almost exclusively CO (Snow & McCall, 2006, ARA&A 44, 367).

See also: → translucent; → cloud.

A type of → interstellar medium cloud where → carbon (C), in → ionized atomic form and protected from → interstellar radiation, transforms into neutral atomic or molecular form. The chemistry in this regime is qualitatively different than in the → diffuse molecular clouds, both because of the decreasing electron fraction and because of the abundance of the highly reactive C atoms.

The translucent cloud regime is the least well understood of all the cloud types. This is partly because of a relative lack of observational data, but also because theoretical models do not all agree on the chemical behavior in this transition region. In some models, there is a zone where the abundance of C exceeds that of C⁺ and CO; in others the peak abundance of C falls below that of C+ and CO. To cope with this uncertainty, Snow & McCall (2006) propose a working definition of translucent cloud material as gas with C⁺ fraction < 0.5 and CO fraction < 0.9. This definition reflects the fact that C+ is no longer the dominant form of carbon as it converts to neutral or molecular form, but also excludes the → dense molecular clouds, where carbon is almost exclusively CO (Snow & McCall, 2006, ARA&A 44, 367).

See also: → translucent; → cloud.

The space beyond the orbit of the Moon. Compare to → cislunar.

Etymology (EN): → trans- + → lunar.

Etymology (PE): Ânsumâhi, ânsumângi, from ânsu “the other side,” from ân “that” + su “side” + mâhi, mângi, → lunar; tarâ-, → trans-.

The space beyond the orbit of the Moon. Compare to → cislunar.

Etymology (EN): → trans- + → lunar.

Etymology (PE): Ânsumâhi, ânsumângi, from ânsu “the other side,” from ân “that” + su “side” + mâhi, mângi, → lunar; tarâ-, → trans-.

1. The act or process of transmitting. The fact of being transmitted.
   

2. The broadcasting of electromagnetic waves from one location to another, as from a transmitter to a receiver.

See also: Verbal noun of → transmit.

1. The act or process of transmitting. The fact of being transmitted.
   

2. The broadcasting of electromagnetic waves from one location to another, as from a transmitter to a receiver.

See also: Verbal noun of → transmit.

The frequency range above the cutoff frequency in a waveguide or transmission line.

See also: → transmission; → band.

The frequency range above the cutoff frequency in a waveguide or transmission line.

See also: → transmission; → band.

The ratio given by the → amplitude (or energy) of a transmitted wave divided by the amplitude (or energy) of the incident wave.

See also: → transmission; → coefficient.

The ratio given by the → amplitude (or energy) of a transmitted wave divided by the amplitude (or energy) of the incident wave.

See also: → transmission; → coefficient.

A diffraction grating that has grooves ruled onto a transparent material so that a beam of light passed through the grating is partly split into spectral orders.

See also: → transmission; → grating.

A diffraction grating that has grooves ruled onto a transparent material so that a beam of light passed through the grating is partly split into spectral orders.

See also: → transmission; → grating.

A decrease in power in transmission from one point to another.

See also: → transmission; → loss.

A decrease in power in transmission from one point to another.

See also: → transmission; → loss.

An assembly of elements which are capable of functioning together to transmit power or signals.

See also: → transmission; → system.

An assembly of elements which are capable of functioning together to transmit power or signals.

See also: → transmission; → system.

To cause (light, heat, sound, etc.) to pass through a medium.

Etymology (EN): M.E. transmitten, from
L. transmittere “send across, transfer, pass on,” from → trans- “across” + mittere “to send.”

Etymology (PE): Tarâgosilidan, infinitive of tarâgosli, from tarâ-→ trans- “across” + gosil “sending away, dismission,” variant gosi; Mid.Pers. wisé “to despatch” (Parthian Mid.Pers. wsys- “to despatch;” Buddhist Mid.Pers. wsydy “to despatch;” Sogdian ‘ns’yd- “to exhort”), from Proto-Iranian *vi-sid- “to despatch, send off,” from prefix vi- “apart, away, out,” + *sid- “to call.”

To cause (light, heat, sound, etc.) to pass through a medium.

Etymology (EN): M.E. transmitten, from
L. transmittere “send across, transfer, pass on,” from → trans- “across” + mittere “to send.”

Etymology (PE): Tarâgosilidan, infinitive of tarâgosli, from tarâ-→ trans- “across” + gosil “sending away, dismission,” variant gosi; Mid.Pers. wisé “to despatch” (Parthian Mid.Pers. wsys- “to despatch;” Buddhist Mid.Pers. wsydy “to despatch;” Sogdian ‘ns’yd- “to exhort”), from Proto-Iranian *vi-sid- “to despatch, send off,” from prefix vi- “apart, away, out,” + *sid- “to call.”

A device or equipment which converts audio, video, or coded signals into modulated radio frequency signals which can be propagated by electromagnetic waves.

See also: Agent noun of → transmit.

A device or equipment which converts audio, video, or coded signals into modulated radio frequency signals which can be propagated by electromagnetic waves.

See also: Agent noun of → transmit.

The act or process of transmuting.
Physics: Any process in which a nuclide is transformed into a different nuclide, usually one of a different element.

See also: Verbal noun of → transmute.

The act or process of transmuting.
Physics: Any process in which a nuclide is transformed into a different nuclide, usually one of a different element.

See also: Verbal noun of → transmute.

To change from one nature, substance, form, or condition into another.

Etymology (EN): M.E., from L. transmutare “to shift,” from → trans-

• mutare “to change,” from PIE base *mei- “to change, go, move;” cf. Av. miθô “inverted, false,” miθaoxta-
  “wrong spoken;” Skt. methati “changes, alternates,
  joins, meets,” mith- “to alternate, meet,” mithás “opposite, in opposition;” L. meare
  “to go, pass,” mutuus “done in exchange;” Goth.
  maidjan “to change;” E. prefix mis- (in mistake).

Etymology (PE): Tarâmutidan, from tarâ-→ trans- + mutidan, from L. mutare, as above.

To change from one nature, substance, form, or condition into another.

Etymology (EN): M.E., from L. transmutare “to shift,” from → trans-

• mutare “to change,” from PIE base *mei- “to change, go, move;” cf. Av. miθô “inverted, false,” miθaoxta-
  “wrong spoken;” Skt. methati “changes, alternates,
  joins, meets,” mith- “to alternate, meet,” mithás “opposite, in opposition;” L. meare
  “to go, pass,” mutuus “done in exchange;” Goth.
  maidjan “to change;” E. prefix mis- (in mistake).

Etymology (PE): Tarâmutidan, from tarâ-→ trans- + mutidan, from L. mutare, as above.

Of or pertaining to the speed of a body in a surrounding fluid when the relative speed of the fluid is → subsonic in some places and → supersonic in others.

See also: → trans-; → sonic.

Of or pertaining to the speed of a body in a surrounding fluid when the relative speed of the fluid is → subsonic in some places and → supersonic in others.

See also: → trans-; → sonic.

Flow of a fluid over a body with a speed in the range just above and below the → Mach number 1.

See also: → transonic; → flow.

Flow of a fluid over a body with a speed in the range just above and below the → Mach number 1.

See also: → transonic; → flow.

Allowing → electromagnetic radiation  of → specific → wavelengths to pass through. See also → translucent.

Etymology (EN): From M.L. transparentem (nominative transparens), pr.p. of transparere “to show through,” from L. → trans- “through” + parere “to come in sight, appear.”

Etymology (PE): Tarânemâ, from tarâ-, → trans-, + nemâ present stem of nemudan “to show” (Mid.Pers. nimūdan, nimây- “to show,” from O.Pers./Av. ni- “down; into,” → ni- (PIE), + māy- “to measure;” cf. Skt. mati “measures,” matra- “measure;”
Gk. metron “measure;” L. metrum; PIE base *me- “to measure”).

Allowing → electromagnetic radiation  of → specific → wavelengths to pass through. See also → translucent.

Etymology (EN): From M.L. transparentem (nominative transparens), pr.p. of transparere “to show through,” from L. → trans- “through” + parere “to come in sight, appear.”

Etymology (PE): Tarânemâ, from tarâ-, → trans-, + nemâ present stem of nemudan “to show” (Mid.Pers. nimūdan, nimây- “to show,” from O.Pers./Av. ni- “down; into,” → ni- (PIE), + māy- “to measure;” cf. Skt. mati “measures,” matra- “measure;”
Gk. metron “measure;” L. metrum; PIE base *me- “to measure”).

An emitter-receiver device that automatically responds upon reception of a designated incoming radar, radio or sonar signal

See also: From trans(mitter), → trans-, + (res)ponder, → responder.

An emitter-receiver device that automatically responds upon reception of a designated incoming radar, radio or sonar signal

See also: From trans(mitter), → trans-, + (res)ponder, → responder.

1. The act of carrying or moving from one place to another.
   

2. To take or carrysomething from one place to another.

Etymology (EN): M.E. transporten, from O.Fr. transporter “to carry or convey across,”
from L. transportare, from → trans- “across” + portare “to carry.”

Etymology (PE): Tarâbord, tarâbari, from tarâ-, → trans-,

• bord, bari, from bordan “to carry, transport;” Mid.Pers. burdan;
  O.Pers./Av. bar- “to bear, carry,” barəθre “to bear (infinitive);” Skt. bharati “he carries;” Gk. pherein “to carry;” L. ferre “to carry;” PIE base *bher- “to carry.”

1. The act of carrying or moving from one place to another.
   

2. To take or carrysomething from one place to another.

Etymology (EN): M.E. transporten, from O.Fr. transporter “to carry or convey across,”
from L. transportare, from → trans- “across” + portare “to carry.”

Etymology (PE): Tarâbord, tarâbari, from tarâ-, → trans-,

• bord, bari, from bordan “to carry, transport;” Mid.Pers. burdan;
  O.Pers./Av. bar- “to bear, carry,” barəθre “to bear (infinitive);” Skt. bharati “he carries;” Gk. pherein “to carry;” L. ferre “to carry;” PIE base *bher- “to carry.”

1. To transfer a mathematical → term from one side of an → equation to the other, with corresponding change of sign.
   

2. Of a → matrix, to interchange → rows and → columns.
   

3. The mathematical object obtained by replacing all → elements a_ij with a_ji.

Etymology (EN): From M.E. transposen, from O.Fr. transposer, from
L. transponere “to place over,” from → trans-

• ponere “to put, place.”

Etymology (PE): Tarânehâdan, tarânehâd, from tarâ-, → trans-,

• nehâdan “to place, put; to set;” Mid.Pers. nihâtan;
  Av. ni- “down; into,” → ni- (PIE),
• dâ- “to put; to establish; to give,” dadâiti “he gives;” cf. Skt. dadâti “he gives;” Gk. didomi “I give;” L. do “I give;” PIE base *do- “to give”).

1. To transfer a mathematical → term from one side of an → equation to the other, with corresponding change of sign.
   

2. Of a → matrix, to interchange → rows and → columns.
   

3. The mathematical object obtained by replacing all → elements a_ij with a_ji.

Etymology (EN): From M.E. transposen, from O.Fr. transposer, from
L. transponere “to place over,” from → trans-

• ponere “to put, place.”

Etymology (PE): Tarânehâdan, tarânehâd, from tarâ-, → trans-,

• nehâdan “to place, put; to set;” Mid.Pers. nihâtan;
  Av. ni- “down; into,” → ni- (PIE),
• dâ- “to put; to establish; to give,” dadâiti “he gives;” cf. Skt. dadâti “he gives;” Gk. didomi “I give;” L. do “I give;” PIE base *do- “to give”).

The matrix of → order n x m obtained from a matrix of order m x n by exchanging the order of the → rows and → columns.

See also: Tansposed, p.p. of → transpose; → matrix.

The matrix of → order n x m obtained from a matrix of order m x n by exchanging the order of the → rows and → columns.

See also: Tansposed, p.p. of → transpose; → matrix.

Math.: A permutation of a set of elements that interchanges two elements and leaves the remaining elements in their original positions. For example, the swapping of 2 and 5 to take the list 123456 to 153426 is a transposition.
Optics: The changing of the relative curves of a lens without changing its refractive value.

See also: → trans-; → position.

Math.: A permutation of a set of elements that interchanges two elements and leaves the remaining elements in their original positions. For example, the swapping of 2 and 5 to take the list 123456 to 153426 is a transposition.
Optics: The changing of the relative curves of a lens without changing its refractive value.

See also: → trans-; → position.

An element beyond uranium in the periodic table, with atomic number greater than 92. Such elements do not occur in nature, but may be obtained by suitable nuclear reactions. They are all radioactive and members of the actinide group.

See also: → trans-; → uranium; → element.

An element beyond uranium in the periodic table, with atomic number greater than 92. Such elements do not occur in nature, but may be obtained by suitable nuclear reactions. They are all radioactive and members of the actinide group.

See also: → trans-; → uranium; → element.

A line that cuts across two or more lines. A transversal cutting two lines generates eight angles, four lying between the two lines, four external to the two lines.

See also: → transverse + → -al.

A line that cuts across two or more lines. A transversal cutting two lines generates eight angles, four lying between the two lines, four external to the two lines.

See also: → transverse + → -al.

Lying or extending crosswise or at right angles to something.
→ transverse velocity; → transverse wave.

Etymology (EN): From L. transversus “turned or directed across,” p.p. of transvertere “to turn across,” from → trans-

• vertere “to turn,” cognate with Pers.
  gardidan “to turn, to change;” Mid.Pers. vartitan; Av. varət- “to turn, revolve;” Skt. vrt- “to turn, roll,” vartate “it turns round, rolls;” O.H.G. werden “to become;” PIE base *wer- “to turn, bend.”

Etymology (PE): Tarâgozar, from tarâ-→ trans- + gozar “passage, transit, passing,” from gozaštan “to pass, cross, transit,” variant gozâštan “to put, to place, let, allow;” Mid.Pers. widardan, widâštan “to pass, to let pass (by);” O.Pers. vitar- “to pass across,” viyatarayam “I put across;” Av. vi-tar- “to pass across,” from vi- “apart, away from” (O.Pers. viy- “apart, away;” Av. vi- “apart, away;” cf. Skt. vi- “apart, asunder, away, out;” L. vitare “to avoid, turn aside”) + O.Pers./Av. tar- “to cross over;” → trans-.

Lying or extending crosswise or at right angles to something.
→ transverse velocity; → transverse wave.

Etymology (EN): From L. transversus “turned or directed across,” p.p. of transvertere “to turn across,” from → trans-

• vertere “to turn,” cognate with Pers.
  gardidan “to turn, to change;” Mid.Pers. vartitan; Av. varət- “to turn, revolve;” Skt. vrt- “to turn, roll,” vartate “it turns round, rolls;” O.H.G. werden “to become;” PIE base *wer- “to turn, bend.”

Etymology (PE): Tarâgozar, from tarâ-→ trans- + gozar “passage, transit, passing,” from gozaštan “to pass, cross, transit,” variant gozâštan “to put, to place, let, allow;” Mid.Pers. widardan, widâštan “to pass, to let pass (by);” O.Pers. vitar- “to pass across,” viyatarayam “I put across;” Av. vi-tar- “to pass across,” from vi- “apart, away from” (O.Pers. viy- “apart, away;” Av. vi- “apart, away;” cf. Skt. vi- “apart, asunder, away, out;” L. vitare “to avoid, turn aside”) + O.Pers./Av. tar- “to cross over;” → trans-.

Same as the → Coulomb gauge.

See also: → transverse; → gauge.

Same as the → Coulomb gauge.

See also: → transverse; → gauge.

In special relativity theory, the mass when the acceleration of a body is perpendicular to its velocity:

m_t = m₀ / [1 - (v/c)²]^1/2,
where m₀ is the → rest mass, v is the velocity, and c the → velocity of light. The transverse mass is identical to the → relativistic mass. See also → longitudinal mass.

See also: → transverse; → mass.

In special relativity theory, the mass when the acceleration of a body is perpendicular to its velocity:

m_t = m₀ / [1 - (v/c)²]^1/2,
where m₀ is the → rest mass, v is the velocity, and c the → velocity of light. The transverse mass is identical to the → relativistic mass. See also → longitudinal mass.

See also: → transverse; → mass.

Same as → tangential velocity.

See also: → transverse; → velocity.

Same as → tangential velocity.

See also: → transverse; → velocity.

A wave in which the vibration or displacement takes place in a plane at right angles to the direction of propagation of the wave; e.g. electromagnetic radiation. → longitudinal wave.

See also: → transverse; → wave.

A wave in which the vibration or displacement takes place in a plane at right angles to the direction of propagation of the wave; e.g. electromagnetic radiation. → longitudinal wave.

See also: → transverse; → wave.

The → Zeeman effect when observed at right angles to the orientation of the magnetic field. Un un-displaced line is observed along with a doublet, three lines in all, with the frequencies ν and
ν ± Δν. The two displaced components correspond to a plane of → polarization parallel to the external magnetic field and the un-displaced line to a plane of polarization perpendicular to this field. → longitudinal Zeeman effect.

See also: → transverse; → Zeeman effect.

The → Zeeman effect when observed at right angles to the orientation of the magnetic field. Un un-displaced line is observed along with a doublet, three lines in all, with the frequencies ν and
ν ± Δν. The two displaced components correspond to a plane of → polarization parallel to the external magnetic field and the un-displaced line to a plane of polarization perpendicular to this field. → longitudinal Zeeman effect.

See also: → transverse; → Zeeman effect.

A four-sided plane figure, no two sides of which are parallel.

Etymology (EN): L.L. trapezium, from Gk. trapezion “irregular quadrilateral,” literally “a little table,” diminutive of trapeza “table,” from shortening of *tetrapeza, from → tetra- “four” + peza “foot, edge,” related to pous, podos, Pers. pâ, → foot.

Etymology (PE): Zuzanaqé, loan from Ar. dhuzanaqat.

A four-sided plane figure, no two sides of which are parallel.

Etymology (EN): L.L. trapezium, from Gk. trapezion “irregular quadrilateral,” literally “a little table,” diminutive of trapeza “table,” from shortening of *tetrapeza, from → tetra- “four” + peza “foot, edge,” related to pous, podos, Pers. pâ, → foot.

Etymology (PE): Zuzanaqé, loan from Ar. dhuzanaqat.

A star cluster located in the center of the → Orion Nebula whose four brightest stars form the vertices of a trapezoid. They are known as θ¹ Ori A, B, C, and D and are of magnitude 6.7, 8.0, 5.1, and 6.7 respectively. They are packed in an area 22 arcseconds across (10,000 A.U.). The Trapezium stars are responsible for the illumination of the entire Orion Nebula. The principal and the most massive star of the group is θ¹Ori C, a young main sequence → O star of type O6. The three others are → B stars. Almost all of the Trapezium stars are multiple: the most massive star θ¹Ori C is double, the next massive star θ¹Ori A is triple, θ¹Ori B is at least quadruple, and θ¹Ori D is apparently single.

See also: → trapezium; → cluster.

A star cluster located in the center of the → Orion Nebula whose four brightest stars form the vertices of a trapezoid. They are known as θ¹ Ori A, B, C, and D and are of magnitude 6.7, 8.0, 5.1, and 6.7 respectively. They are packed in an area 22 arcseconds across (10,000 A.U.). The Trapezium stars are responsible for the illumination of the entire Orion Nebula. The principal and the most massive star of the group is θ¹Ori C, a young main sequence → O star of type O6. The three others are → B stars. Almost all of the Trapezium stars are multiple: the most massive star θ¹Ori C is double, the next massive star θ¹Ori A is triple, θ¹Ori B is at least quadruple, and θ¹Ori D is apparently single.

See also: → trapezium; → cluster.

1. The act of traveling, especially to a distant place.
   

   2. To go, move, or journey from one place to another.

Etymology (EN): M.E. from travailen “to make a journey,” originally the same word as Fr. travail “work, labor” (by shift to “make a laborious journey”).

Etymology (PE): Safar, from Ar.

1. The act of traveling, especially to a distant place.
   

   2. To go, move, or journey from one place to another.

Etymology (EN): M.E. from travailen “to make a journey,” originally the same word as Fr. travail “work, labor” (by shift to “make a laborious journey”).

Etymology (PE): Safar, from Ar.

(British: traveller) A person or thing that travels.

See also: → travel; → -er.

(British: traveller) A person or thing that travels.

See also: → travel; → -er.

1. A tall, woody perennial plant usually with a single trunk.
   

   2. Math.: → factor tree.
      

   3. A → data structure that is used to represent hierarchical data.
      

   4. In → graph theory, a → connected graph with no → cycles.
      

   5. A mathematical structure that can be viewed as either a graph or as a data structure. Many powerful algorithms in computer science and software engineering are tree based algorithms.

Etymology (EN): M.E., from O.E. treo, treow “tree, wood,” from P.Gmc. *trewan (cf. O.S. trio, O.N. tre, Goth. triu), from PIE *deru- “wood” (cf. Mod.Pers. dâr “tree;” O.Pers. dāruv- “wood;” Av. dāuru- “piece of wood, tree trunk;” Skt. dāru- “tree, wood;”
Gk. drus “tree;” Serb. drvo “tree;” L. larix “larch tree;”
Rus. drevo “tree, wood;” Pol. drwa “wood;” Lith. derva “pine wood;” O.Ir. daur, Welsh derwen “oak”).

Etymology (PE): Deraxt “tree;” Mid.Pers. draxt “tree,” two possible etymologies. A suffixed variant of dâr “tree,” cognate with E. tree, as above. Alternatively, from Av. *draxta- “firmly stood, fixed” (as in handraxta-), from drang-, dranj- “to fix, fasten, strengthen, hold,” dražaite “holds,” infinitive drājnhe; cf. Khotanese drys- “to hold;” Sogdian drγ- “to hold;” Parthian Mid.Pers. drxs “to endure.”

1. A tall, woody perennial plant usually with a single trunk.
   

   2. Math.: → factor tree.
      

   3. A → data structure that is used to represent hierarchical data.
      

   4. In → graph theory, a → connected graph with no → cycles.
      

   5. A mathematical structure that can be viewed as either a graph or as a data structure. Many powerful algorithms in computer science and software engineering are tree based algorithms.

Etymology (EN): M.E., from O.E. treo, treow “tree, wood,” from P.Gmc. *trewan (cf. O.S. trio, O.N. tre, Goth. triu), from PIE *deru- “wood” (cf. Mod.Pers. dâr “tree;” O.Pers. dāruv- “wood;” Av. dāuru- “piece of wood, tree trunk;” Skt. dāru- “tree, wood;”
Gk. drus “tree;” Serb. drvo “tree;” L. larix “larch tree;”
Rus. drevo “tree, wood;” Pol. drwa “wood;” Lith. derva “pine wood;” O.Ir. daur, Welsh derwen “oak”).

Etymology (PE): Deraxt “tree;” Mid.Pers. draxt “tree,” two possible etymologies. A suffixed variant of dâr “tree,” cognate with E. tree, as above. Alternatively, from Av. *draxta- “firmly stood, fixed” (as in handraxta-), from drang-, dranj- “to fix, fasten, strengthen, hold,” dražaite “holds,” infinitive drājnhe; cf. Khotanese drys- “to hold;” Sogdian drγ- “to hold;” Parthian Mid.Pers. drxs “to endure.”

A type of → data structure in which each element is attached to one or more elements in a hierarchical manner. Trees are often called inverted trees because they are normally drawn with the root at the top.

See also: → tree; → structure.

A type of → data structure in which each element is attached to one or more elements in a hierarchical manner. Trees are often called inverted trees because they are normally drawn with the root at the top.

See also: → tree; → structure.

A graphical representation that displays a hierarchical view of data.

See also: → tree; → view.

A graphical representation that displays a hierarchical view of data.

See also: → tree; → view.

A general tendency, course, or direction.

Etymology (EN): From M.E. trenden “to roll about, turn, revolve,” from O.E. trendan, (cf. O.E. trinde “round lump, ball,” O.Fris. trind, M.L.G. trint “round,” M.L.G. trent “ring, boundary,” Du. trent “circumference,” Dan. trind “round”).

Etymology (PE): Ravâl, from row present stem of raftan “to go, walk, proceed” (Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- “to go; to attack”) + suffix -âl, → -al.

A general tendency, course, or direction.

Etymology (EN): From M.E. trenden “to roll about, turn, revolve,” from O.E. trendan, (cf. O.E. trinde “round lump, ball,” O.Fris. trind, M.L.G. trint “round,” M.L.G. trent “ring, boundary,” Du. trent “circumference,” Dan. trind “round”).

Etymology (PE): Ravâl, from row present stem of raftan “to go, walk, proceed” (Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- “to go; to attack”) + suffix -âl, → -al.

In medieval astronomy, a spurious oscillatory motion of the equinoxes thought to have a period of 7,000 years. This concept, attributed to Thâbit ibn Qurra (c. 830-901),
had a profound influence on medieval astronomy. In order to explain trepidation, Thâbit was said to have added a new sphere to the eight Ptolemaic spheres beyond the sphere of fixed stars.

Etymology (EN): From L. trepidationem “agitation, trembling,” from trepidare “to tremble, hurry,” from trepidus “anxious, scared;” cf. Skt. trprá- “hasty;” PIE base *trep- “to shake, tremble.”

Etymology (PE): Larzeš, verbal noun of larzidan “to tremble, shiver;” Mid.Pers. larzidan “to shake, tremble;” Manichean Mid.Pers. rarz- “to shiver with fever;” Proto-Iranian *rarz- “to shake, tremble.”

In medieval astronomy, a spurious oscillatory motion of the equinoxes thought to have a period of 7,000 years. This concept, attributed to Thâbit ibn Qurra (c. 830-901),
had a profound influence on medieval astronomy. In order to explain trepidation, Thâbit was said to have added a new sphere to the eight Ptolemaic spheres beyond the sphere of fixed stars.

Etymology (EN): From L. trepidationem “agitation, trembling,” from trepidare “to tremble, hurry,” from trepidus “anxious, scared;” cf. Skt. trprá- “hasty;” PIE base *trep- “to shake, tremble.”

Etymology (PE): Larzeš, verbal noun of larzidan “to tremble, shiver;” Mid.Pers. larzidan “to shake, tremble;” Manichean Mid.Pers. rarz- “to shiver with fever;” Proto-Iranian *rarz- “to shake, tremble.”

1. Law: An unlawful act causing injury to the person, property, or rights of another, committed with force or violence, actual or implied.
   → light trespass.
   

2. To commit a transgression or offense; transgress; offend; sin (Dictionary.com).

Etymology (EN): M.E. trespas, from O.Fr. trespasser “pass beyond or across, cross, traverse; infringe, violate,” from tres- “beyond,” from L. → trans-, + passer “go by, pass,” → pass, → passage.

Etymology (PE): Tarâraft, tarâraftan, from tarâ-, → trans-,

• raft, raftan “to go,” → process.

1. Law: An unlawful act causing injury to the person, property, or rights of another, committed with force or violence, actual or implied.
   → light trespass.
   

2. To commit a transgression or offense; transgress; offend; sin (Dictionary.com).

Etymology (EN): M.E. trespas, from O.Fr. trespasser “pass beyond or across, cross, traverse; infringe, violate,” from tres- “beyond,” from L. → trans-, + passer “go by, pass,” → pass, → passage.

Etymology (PE): Tarâraft, tarâraftan, from tarâ-, → trans-,

• raft, raftan “to go,” → process.

The plane figure formed by three lines intersecting in pairs at three points; a three-sided → polygon. → equilateral triangle, → isosceles triangle, → scalene triangle.

Etymology (EN): M.E., from O.Fr. triangle, from L. triangulum “triangle,” from neuter of adj. triangulus “three-cornered,” from tri-, → three, + angulus “corner,” → angle.

Etymology (PE): Seguš “three-cornered,” from sé, → three,

• guš “corner, → angle.”
  Sebar “three-sided,” from sé, → three,
• bar “→ side; breadth; breast.”

The plane figure formed by three lines intersecting in pairs at three points; a three-sided → polygon. → equilateral triangle, → isosceles triangle, → scalene triangle.

Etymology (EN): M.E., from O.Fr. triangle, from L. triangulum “triangle,” from neuter of adj. triangulus “three-cornered,” from tri-, → three, + angulus “corner,” → angle.

Etymology (PE): Seguš “three-cornered,” from sé, → three,

• guš “corner, → angle.”
  Sebar “three-sided,” from sé, → three,
• bar “→ side; breadth; breast.”

1. A theorem according to which any side of a triangle is always shorter than the sum of the other two sides.
   

2. The third requirement for a → distance function describing a → metric space.

See also: → triangle; → inequality.

1. A theorem according to which any side of a triangle is always shorter than the sum of the other two sides.
   

2. The third requirement for a → distance function describing a → metric space.

See also: → triangle; → inequality.

In surveying and navigation, the process of deriving the linear distance between any two remote points by the division of a large area into adjacent triangles and
using trigonometric relationships. See also → trilateration.

Etymology (EN): From M.L. triangulation-, from triangulare “to make triangles,” → triangle.

Etymology (PE): Seguš-bandi, from sé, → three, + guš/gušé, → angle, + bandi verbal noun from bastan “to form, bind, tie” (Mid.Pers. bastan/vastan “to bind, shut;” Av./O.Pers. band- “to bind, fetter,” banda- “band, tie;” cf. Skt. bandh- “to bind, tie, fasten;” Ger. binden; E. bind; PIE base *bhendh- “to bind”).

In surveying and navigation, the process of deriving the linear distance between any two remote points by the division of a large area into adjacent triangles and
using trigonometric relationships. See also → trilateration.

Etymology (EN): From M.L. triangulation-, from triangulare “to make triangles,” → triangle.

Etymology (PE): Seguš-bandi, from sé, → three, + guš/gušé, → angle, + bandi verbal noun from bastan “to form, bind, tie” (Mid.Pers. bastan/vastan “to bind, shut;” Av./O.Pers. band- “to bind, fetter,” banda- “band, tie;” cf. Skt. bandh- “to bind, tie, fasten;” Ger. binden; E. bind; PIE base *bhendh- “to bind”).

The Triangle. A small northern constellation between → Andromeda and → Aries, at 2h right ascension, 32° north declination.
Its three brightest stars, of magnitudes 3.0, 3.4, and 4.0, form a small, elongated isosceles triangle. One of the constellations listed by Ptolemy.
The famous → spiral galaxy → M33 lies in Triangulum. Abbreviation: Tri; genitive: Trianguli.

See also: → triangle.

The Triangle. A small northern constellation between → Andromeda and → Aries, at 2h right ascension, 32° north declination.
Its three brightest stars, of magnitudes 3.0, 3.4, and 4.0, form a small, elongated isosceles triangle. One of the constellations listed by Ptolemy.
The famous → spiral galaxy → M33 lies in Triangulum. Abbreviation: Tri; genitive: Trianguli.

See also: → triangle.

The Southern Triangle. A small constellation in the southern hemisphere, at 16h right ascension, 65° south declination, introduced by Johann Bayer (1603). Abbreviation: TrA; genitive: Trianguli Australe

Etymology (EN): → traingle; Australe “southern,” from auster “south wind,” metaphorically extended to “south.”

Etymology (PE): Sebar, → traingle; daštari→ southern.

The Southern Triangle. A small constellation in the southern hemisphere, at 16h right ascension, 65° south declination, introduced by Johann Bayer (1603). Abbreviation: TrA; genitive: Trianguli Australe

Etymology (EN): → traingle; Australe “southern,” from auster “south wind,” metaphorically extended to “south.”

Etymology (PE): Sebar, → traingle; daštari→ southern.

One of the prominent members of the → Local Group situated in the constellation → Triangulum. Also know as NGC 598. M33 is a type Sc → spiral galaxy seen nearly → face-on. It lies 2.8 million → light-years away and its diameter is 52,000 light-years. M33 is thought to be a satellite of the → Andromeda Galaxy.

See also: → Triangulum; → galaxy.

One of the prominent members of the → Local Group situated in the constellation → Triangulum. Also know as NGC 598. M33 is a type Sc → spiral galaxy seen nearly → face-on. It lies 2.8 million → light-years away and its diameter is 52,000 light-years. M33 is thought to be a satellite of the → Andromeda Galaxy.

See also: → Triangulum; → galaxy.

The hydrogen molecule composed of three atoms in which one of the atoms is ionized. The molecular ion H₃⁺ plays a key role in the
chemistry of gaseous → interstellar medium. It reacts efficiently with almost any neutral atom or molecule to initiate a network of ion-neutral reactions. It is responsible for producing molecules such as OH, CO, and H₂O. The first detection of H₃⁺ in the interstellar medium, via two closely spaced absorption lines (doublet) near 3.668 μm, were reported in two dense → molecular cloud cores along the lines of sight to the embedded → young stellar objects W33A and GL2136 (Geballe & Oka 1996). Since then H₃⁺ has been detected in several molecular clouds. It is believed that H₃⁺ forms via → cosmic ray → ionization
of H₂ producing H₂⁺, which quickly reacts to another H₂ molecule to form H₃⁺ ( H₂ + CR → H₂⁺ and H₂⁺ + H₂→ H₃⁺ + H + 1.7 eV).

See also: Tri-, → three; → atomic; → hydrogen; → molecular; → ion.

The hydrogen molecule composed of three atoms in which one of the atoms is ionized. The molecular ion H₃⁺ plays a key role in the
chemistry of gaseous → interstellar medium. It reacts efficiently with almost any neutral atom or molecule to initiate a network of ion-neutral reactions. It is responsible for producing molecules such as OH, CO, and H₂O. The first detection of H₃⁺ in the interstellar medium, via two closely spaced absorption lines (doublet) near 3.668 μm, were reported in two dense → molecular cloud cores along the lines of sight to the embedded → young stellar objects W33A and GL2136 (Geballe & Oka 1996). Since then H₃⁺ has been detected in several molecular clouds. It is believed that H₃⁺ forms via → cosmic ray → ionization
of H₂ producing H₂⁺, which quickly reacts to another H₂ molecule to form H₃⁺ ( H₂ + CR → H₂⁺ and H₂⁺ + H₂→ H₃⁺ + H + 1.7 eV).

See also: Tri-, → three; → atomic; → hydrogen; → molecular; → ion.

The property of some crystals of exhibiting three different colors when viewed from three different directions under white lights. → dichroism.

Etymology (EN): From Gk. tri- “three” + chroic, from chroma “color” + -ism.

Etymology (PE): Sefâmi, from se, → three, + fâm “color,”

• -i noun suffix.

The property of some crystals of exhibiting three different colors when viewed from three different directions under white lights. → dichroism.

Etymology (EN): From Gk. tri- “three” + chroic, from chroma “color” + -ism.

Etymology (PE): Sefâmi, from se, → three, + fâm “color,”

• -i noun suffix.

A large luminous → H II region in the constellation → Sagittarius. Also known as M20, NGC 6514. Conspicuous → dust lanes radiating from the center appear to divide the nebula in three → lobes. It is a combined → emission nebula and → reflection nebula, extending for nearly 30’ on the sky. Its estimated distance is 4100±200 → light-years (Kuhn et al., 2018, arXiv:1807.02115).

Etymology (EN): Trifid, from L. trifidus “split in three,” from → tri- + fidus “divided,” from findere “to split;” → nebula.

Etymology (PE): Miq, → nebula; sepâré “split in three,” from sé, → three, + pâré “piece, part, portion, fragment;” Mid.Pers. pârag “piece, part, portion; gift, offering, bribe;” Av. pāra- “debt,” from par- “to remunerate, equalize; to condemn;” PIE *per- “to sell, hand over, distribute; to assigne;” cf. L. pars “part, piece, side, share,” portio “share, portion;” Gk. peprotai “it has been granted;” Skt. purti- “reward;” Hitt. pars-, parsiya- “to break, crumble.”

A large luminous → H II region in the constellation → Sagittarius. Also known as M20, NGC 6514. Conspicuous → dust lanes radiating from the center appear to divide the nebula in three → lobes. It is a combined → emission nebula and → reflection nebula, extending for nearly 30’ on the sky. Its estimated distance is 4100±200 → light-years (Kuhn et al., 2018, arXiv:1807.02115).

Etymology (EN): Trifid, from L. trifidus “split in three,” from → tri- + fidus “divided,” from findere “to split;” → nebula.

Etymology (PE): Miq, → nebula; sepâré “split in three,” from sé, → three, + pâré “piece, part, portion, fragment;” Mid.Pers. pârag “piece, part, portion; gift, offering, bribe;” Av. pāra- “debt,” from par- “to remunerate, equalize; to condemn;” PIE *per- “to sell, hand over, distribute; to assigne;” cf. L. pars “part, piece, side, share,” portio “share, portion;” Gk. peprotai “it has been granted;” Skt. purti- “reward;” Hitt. pars-, parsiya- “to break, crumble.”

1a) (n.) Anything, as an act or event, that serves as a stimulus and initiates or precipitates a reaction or series of reactions.
1b) In electronics, the signal or stimulus that initiates a → trigger circuit.
2) (v.) To initiate or precipitate (a chain of events, scientific reaction, psychological process, etc.).

Etymology (EN): Earlier tricker, from Du. trekker “trigger,” from trekken “to pull,” from M.Du. trecken (cf. M.L.G. trecken, O.H.G. trechan “to draw”).

Etymology (PE): 1) Mâšé “a trigger, tongs, pincers,” of unknown origin.

2. Mâšidan, infinitive from mâšé, as above.

1a) (n.) Anything, as an act or event, that serves as a stimulus and initiates or precipitates a reaction or series of reactions.
1b) In electronics, the signal or stimulus that initiates a → trigger circuit.
2) (v.) To initiate or precipitate (a chain of events, scientific reaction, psychological process, etc.).

Etymology (EN): Earlier tricker, from Du. trekker “trigger,” from trekken “to pull,” from M.Du. trecken (cf. M.L.G. trecken, O.H.G. trechan “to draw”).

Etymology (PE): 1) Mâšé “a trigger, tongs, pincers,” of unknown origin.

2. Mâšidan, infinitive from mâšé, as above.

A circuit in which a specific predetermined action is initiated by an input pulse.

See also: → trigger; → circuit

A circuit in which a specific predetermined action is initiated by an input pulse.

See also: → trigger; → circuit

The formation of second-generation stars in a → molecular cloud, as set off by the action of → massive stars. → sequential star formation; → radiation-driven implosion.

See also: → trigger; → star formation.

The formation of second-generation stars in a → molecular cloud, as set off by the action of → massive stars. → sequential star formation; → radiation-driven implosion.

See also: → trigger; → star formation.

Relating to or used in → trigonometry. → trigonometric function.

See also: → trigonometry; → -ic.

Relating to or used in → trigonometry. → trigonometric function.

See also: → trigonometry; → -ic.

A function of an angle, one of six functions (sine, cosine, tangent, cotangent, secant, and cosecant) that represent ratios of sides of right triangles. Also called circular function.

See also: → trigonometric; → function.

A function of an angle, one of six functions (sine, cosine, tangent, cotangent, secant, and cosecant) that represent ratios of sides of right triangles. Also called circular function.

See also: → trigonometric; → function.

The → parallax of a nearby star (less than 300 → light-years) against the background of more distant stars resulting from the motion of the Earth in its orbit around the Sun.

See also: → trigonometric; → parallax.

The → parallax of a nearby star (less than 300 → light-years) against the background of more distant stars resulting from the motion of the Earth in its orbit around the Sun.

See also: → trigonometric; → parallax.

The branch of mathematics dealing with the relations of the sides and angles of triangles; also the various algebraic functions of these relations.

Etymology (EN): From N.L. trigonometria, from Gk. trigonon “triangle” (from tri-, → three, + gonia “angle,” cognate with Pers. zânu “knee”) + metron,
→ -metry.

Etymology (PE): Sebarsanji, from sebar, → trianle, + -sanji, → -metry.

The branch of mathematics dealing with the relations of the sides and angles of triangles; also the various algebraic functions of these relations.

Etymology (EN): From N.L. trigonometria, from Gk. trigonon “triangle” (from tri-, → three, + gonia “angle,” cognate with Pers. zânu “knee”) + metron,
→ -metry.

Etymology (PE): Sebarsanji, from sebar, → trianle, + -sanji, → -metry.

A geometrical method in land surveying for the determination of the relative position of points. In contrast to → triangulation, trilateration involves measuring the lengths of the three sides of touching or overlapping triangles and not their angles.

See also: → tri-; → lateral; → side; → -tion.

A geometrical method in land surveying for the determination of the relative position of points. In contrast to → triangulation, trilateration involves measuring the lengths of the three sides of touching or overlapping triangles and not their angles.

See also: → tri-; → lateral; → side; → -tion.

In composition, having three nitro groups (NO₂), especially replacing hydrogen. → trinitrotoluene.

See also: From L. tri-, a combining form meaning → three

• nitro- a combining form used in the names of chemical compounds in which the nitro group is present.

In composition, having three nitro groups (NO₂), especially replacing hydrogen. → trinitrotoluene.

See also: From L. tri-, a combining form meaning → three

• nitro- a combining form used in the names of chemical compounds in which the nitro group is present.

A yellow, solid chemical compound, that does not occur naturally in the environment. More specifically, 2,4,6-trinitrotoluene
(C₆H₂(NO₂)₃CH₃),
is commonly known as TNT. It is an explosive extensively used in munitions and for demolitions.

See also: → trinitro- + → toluene.

A yellow, solid chemical compound, that does not occur naturally in the environment. More specifically, 2,4,6-trinitrotoluene
(C₆H₂(NO₂)₃CH₃),
is commonly known as TNT. It is an explosive extensively used in munitions and for demolitions.

See also: → trinitro- + → toluene.

1. A → polynomial that consists of three terms.
   

2. Of, pertaining to, or consisting of a trinomial.

See also: → tri- + nomial, short for → nomnial.

1. A → polynomial that consists of three terms.
   

2. Of, pertaining to, or consisting of a trinomial.

See also: → tri- + nomial, short for → nomnial.

A compound → vowel sound resulting from the succession of three simple vowels pronounced in a single syllable (as in power, hour, fire).

See also: Tri-, → three; → diphthong.

A compound → vowel sound resulting from the succession of three simple vowels pronounced in a single syllable (as in power, hour, fire).

See also: Tri-, → three; → diphthong.

Threefold; consisting of three parts.
→ triple alpha process; → triple conjunction; → triple point; → triple star.

Etymology (EN): M.E., from M.L. triplare “to triple,” from L. triplus “threefold, triple,” from tri-, → three,

• -plus “-fold.”

Etymology (PE): Setâyi, from setâ, from sé→ three + tâ “fold, plait, ply; piece, part,” Mid.Pers. tâg “piece, part.”

Threefold; consisting of three parts.
→ triple alpha process; → triple conjunction; → triple point; → triple star.

Etymology (EN): M.E., from M.L. triplare “to triple,” from L. triplus “threefold, triple,” from tri-, → three,

• -plus “-fold.”

Etymology (PE): Setâyi, from setâ, from sé→ three + tâ “fold, plait, ply; piece, part,” Mid.Pers. tâg “piece, part.”

A chain of nuclear fusion reactions by which three helium nuclei (→ alpha particles) are transformed into → carbon. First two nuclei of helium
collide, fuse, and form a nucleus of → beryllium: ⁴He + ⁴He ↔ ⁸Be, which is unstable and will decay back into two helium nuclei within a few 10^-17 seconds. However, due to sufficiently high density and temperature in the stellar core, during a third collision between beryllium and helium, carbon is formed: ⁸Be + ⁴He → ¹²C + γ. The triple-alpha process is possible owing to the existence of the → Hoyle state. It is the main source of energy production in → red giants and → red supergiants in which the core temperature has reached at least 100 million K. Also called → Salpeter process.

See also: → triple; → alpha particle; → process.

A chain of nuclear fusion reactions by which three helium nuclei (→ alpha particles) are transformed into → carbon. First two nuclei of helium
collide, fuse, and form a nucleus of → beryllium: ⁴He + ⁴He ↔ ⁸Be, which is unstable and will decay back into two helium nuclei within a few 10^-17 seconds. However, due to sufficiently high density and temperature in the stellar core, during a third collision between beryllium and helium, carbon is formed: ⁸Be + ⁴He → ¹²C + γ. The triple-alpha process is possible owing to the existence of the → Hoyle state. It is the main source of energy production in → red giants and → red supergiants in which the core temperature has reached at least 100 million K. Also called → Salpeter process.

See also: → triple; → alpha particle; → process.

A rare event involving a particularly intricate set of movements of two planets or a planet and a star where they meet each other three times in a short period either in opposition or at the time of inferior conjunction, if an inferior planet is involved. The visible movement of the planet or the planets in the sky is therefore normally prograde at the first conjunction, retrograde at the second conjunction and again prograde at the third conjunction.

See also: → triple; → conjunction.

A rare event involving a particularly intricate set of movements of two planets or a planet and a star where they meet each other three times in a short period either in opposition or at the time of inferior conjunction, if an inferior planet is involved. The visible movement of the planet or the planets in the sky is therefore normally prograde at the first conjunction, retrograde at the second conjunction and again prograde at the third conjunction.

See also: → triple; → conjunction.

The definite pressure and temperature at which all three phases of a substance coexist in → phase equilibrium. The triple point of water has a pressure of 4.58 mm of Hg and a temperature of 273.16 °K.

Etymology (EN): → triple; → point.

Etymology (PE): Noqté, → triple; segâné, from sé→ three + -gâné suffix forming plural entities, from Mid.Pers. -gânag, -gâna.

The definite pressure and temperature at which all three phases of a substance coexist in → phase equilibrium. The triple point of water has a pressure of 4.58 mm of Hg and a temperature of 273.16 °K.

Etymology (EN): → triple; → point.

Etymology (PE): Noqté, → triple; segâné, from sé→ three + -gâné suffix forming plural entities, from Mid.Pers. -gânag, -gâna.

A group of three stars visually or physically associated with each other. → triple system.

See also: → triple; → star

A group of three stars visually or physically associated with each other. → triple system.

See also: → triple; → star

A system of three stars which are physically associated among them.

See also: → triple; → system

A system of three stars which are physically associated among them.

See also: → triple; → system

A group or set of three of one kind.
Optics: A compound lens made up of three elements that may or may not be cemented.

Etymology (EN): From trip-, from → triple + -et, from → doublet.

Etymology (PE): Setâyé, from setâ, → triple, + -(y)é nuance suffix.

A group or set of three of one kind.
Optics: A compound lens made up of three elements that may or may not be cemented.

Etymology (EN): From trip-, from → triple + -et, from → doublet.

Etymology (PE): Setâyé, from setâ, → triple, + -(y)é nuance suffix.

The electronic state of an atom or molecule which has two unpaired electrons, and therefore whose total spin angular momentum is equal to 1.

See also: → triplet; → state.

The electronic state of an atom or molecule which has two unpaired electrons, and therefore whose total spin angular momentum is equal to 1.

See also: → triplet; → state.

An ancient astronomical instrument first described by Ptolemy in the Almagest, used in measuring the → altitude of a celestial body. It consisted of three long arms of wood. The first is perpendicular to the → horizon; the second is connected at the head of the first with an axis. The third had a graduated scale. An object was sighted along one arm and its → zenith distance was read on the graduated scale.
It performed the same function as the → quadrant. Also called parallactic rulers, Ptolemy’s rulers.

Etymology (EN): L. neuter of triquetrus “three corned,” from tri-→ three + -quetrus “corned.”

Etymology (PE): Se-šâx, literally “three corned,” from se,
→ three, + šâx “→ branch, horn.”

An ancient astronomical instrument first described by Ptolemy in the Almagest, used in measuring the → altitude of a celestial body. It consisted of three long arms of wood. The first is perpendicular to the → horizon; the second is connected at the head of the first with an axis. The third had a graduated scale. An object was sighted along one arm and its → zenith distance was read on the graduated scale.
It performed the same function as the → quadrant. Also called parallactic rulers, Ptolemy’s rulers.

Etymology (EN): L. neuter of triquetrus “three corned,” from tri-→ three + -quetrus “corned.”

Etymology (PE): Se-šâx, literally “three corned,” from se,
→ three, + šâx “→ branch, horn.”

Unstable heavy → isotope of → hydrogen whose nucleus contains one → proton and two → neutrons. Tritium occurs naturally due to → cosmic rays interacting with atmospheric gases. In the most important reaction for natural tritium production, a fast neutron interacts with atmospheric nitrogen: ¹⁴N + n → ¹²C + ³T. Its → half-life is about 12 years. Tritium was formed in an intermediate step in light element synthesis in → early Universe.

See also: N.L., from Gk. trit(os) “third” (from → tri-

• -tos adj. suffix) + N.L. → -ium.

Unstable heavy → isotope of → hydrogen whose nucleus contains one → proton and two → neutrons. Tritium occurs naturally due to → cosmic rays interacting with atmospheric gases. In the most important reaction for natural tritium production, a fast neutron interacts with atmospheric nitrogen: ¹⁴N + n → ¹²C + ³T. Its → half-life is about 12 years. Tritium was formed in an intermediate step in light element synthesis in → early Universe.

See also: N.L., from Gk. trit(os) “third” (from → tri-

• -tos adj. suffix) + N.L. → -ium.

The seventh and the largest of → Neptune’s satellites. It has a diameter of 2,700 km and orbits its planet at a mean distance of 354,760 km every 5.877 days. Triton was discovered by William Lassell in 1846 scarcely a month after Neptune was discovered. Triton is colder than any other measured object in the solar system with a surface temperature of -235° C. It has an extremely thin atmosphere. Nitrogen ice particles might form thin clouds a few kilometers above the surface. The atmospheric pressure at Triton’s surface is about 15 microbars, 0.000015 times the sea-level surface pressure on Earth. Triton is the only large satellite in the solar system to circle a planet in a → retrograde motion, that is in a direction opposite to the rotation of the planet.

See also: In Gk. mythology, Triton is a god of the sea, the son of Poseidon (Neptune); usually portrayed as having the head and trunk of a man and the tail of a fish.

The seventh and the largest of → Neptune’s satellites. It has a diameter of 2,700 km and orbits its planet at a mean distance of 354,760 km every 5.877 days. Triton was discovered by William Lassell in 1846 scarcely a month after Neptune was discovered. Triton is colder than any other measured object in the solar system with a surface temperature of -235° C. It has an extremely thin atmosphere. Nitrogen ice particles might form thin clouds a few kilometers above the surface. The atmospheric pressure at Triton’s surface is about 15 microbars, 0.000015 times the sea-level surface pressure on Earth. Triton is the only large satellite in the solar system to circle a planet in a → retrograde motion, that is in a direction opposite to the rotation of the planet.

See also: In Gk. mythology, Triton is a god of the sea, the son of Poseidon (Neptune); usually portrayed as having the head and trunk of a man and the tail of a fish.

1. Of very little importance or value; insignificant; commonplace; ordinary.
   

2a) Math.: A solution of an equation in which the value of every variable of the equation is equal to zero. For example, x² + 2y² = x + 3y has a trivial solution x = 0, y = 0.

2b) Of a theorem or proof: simple, transparent, or immediately evident.

Any theorem once a proof has been obtained, no matter how difficult the theorem was to prove in the beginning.

2c) For any natural number, the number itself and 1 which are called trivial divisors.

3. Chemistry: → trivial name.

Etymology (EN): From M.L. trivialis “found everywhere, commonplace; known by every body,” from trivium literally “crossroad, a place where three roads meet,” also “the lower division of the seven liberal arts taught in medieval universities, i.e. grammar, rhetoric, and logic,” from tri-, → three, + via “road,” since it was common in Roman Empire for three roads to meet.

Etymology (PE): Zab “easy, unbought, gratis; straight,” variant zap, related to sabok “light, not heavy; unsteady;” Proto-Iranian *θrap-/tarp- “to be unsteady;” cf. Kurd. terpin “to stumble;” Pashto drabəl “to shake, press down;” Skt. trepa- “hasty;”
Gk. trepein “to turn;” L. trepidus “agitated, anxious;” PIE *trep- “to shake, tremble.”

1. Of very little importance or value; insignificant; commonplace; ordinary.
   

2a) Math.: A solution of an equation in which the value of every variable of the equation is equal to zero. For example, x² + 2y² = x + 3y has a trivial solution x = 0, y = 0.

2b) Of a theorem or proof: simple, transparent, or immediately evident.

Any theorem once a proof has been obtained, no matter how difficult the theorem was to prove in the beginning.

2c) For any natural number, the number itself and 1 which are called trivial divisors.

3. Chemistry: → trivial name.

Etymology (EN): From M.L. trivialis “found everywhere, commonplace; known by every body,” from trivium literally “crossroad, a place where three roads meet,” also “the lower division of the seven liberal arts taught in medieval universities, i.e. grammar, rhetoric, and logic,” from tri-, → three, + via “road,” since it was common in Roman Empire for three roads to meet.

Etymology (PE): Zab “easy, unbought, gratis; straight,” variant zap, related to sabok “light, not heavy; unsteady;” Proto-Iranian *θrap-/tarp- “to be unsteady;” cf. Kurd. terpin “to stumble;” Pashto drabəl “to shake, press down;” Skt. trepa- “hasty;”
Gk. trepein “to turn;” L. trepidus “agitated, anxious;” PIE *trep- “to shake, tremble.”

Chemistry: A common name for a chemical compound derived
from the natural source, or of historic origin, and not according to the systematic nomenclature. For example, the trivial name of sodium chloride is → salt.

See also: → trivial; → name.

Chemistry: A common name for a chemical compound derived
from the natural source, or of historic origin, and not according to the systematic nomenclature. For example, the trivial name of sodium chloride is → salt.

See also: → trivial; → name.

The quality or state of being → trivial; something trivial.

See also: → trivial; → -ity;.

The quality or state of being → trivial; something trivial.

See also: → trivial; → -ity;.

To make → trivial.

See also: → trivial; → -ize

To make → trivial.

See also: → trivial; → -ize

A member of the family of asteroids that share → Jupiter’s orbit and lie in elongated, curved regions around the two → Lagrangian points 60° ahead and behind of Jupiter. The Lagrangian points L4 and L5 host several thousands of them. Originally, the term Trojan applied only to asteroids sharing Jupiter’s orbit; however, planetoidal bodies have been discovered at the Lagrangian points of Mars and Neptune as well, and are also referred to as → Mars Trojans and Neptune Trojans respectively.

Etymology (EN): M.E.; O.E. Troian, from Trojanus, from Troj(a) “Troy”

• -anus; → asteroid.

Etymology (PE): Sayyârakhâ plural of sayyârak, → asteroid; Troâ-yi adj. of Troâ “Troy.”

A member of the family of asteroids that share → Jupiter’s orbit and lie in elongated, curved regions around the two → Lagrangian points 60° ahead and behind of Jupiter. The Lagrangian points L4 and L5 host several thousands of them. Originally, the term Trojan applied only to asteroids sharing Jupiter’s orbit; however, planetoidal bodies have been discovered at the Lagrangian points of Mars and Neptune as well, and are also referred to as → Mars Trojans and Neptune Trojans respectively.

Etymology (EN): M.E.; O.E. Troian, from Trojanus, from Troj(a) “Troy”

• -anus; → asteroid.

Etymology (PE): Sayyârakhâ plural of sayyârak, → asteroid; Troâ-yi adj. of Troâ “Troy.”

Either of the two parallels of latitude on Earth at which the Sun appears overhead at the → summer and → winter solstices each year: → Tropic of Cancer, → Tropic of Capricorn . The tropics lie at latitudes 23°26’, north and south, an angle defined by the Earth’s → axial inclination.

Etymology (EN): M.E., from L. tropicus, from Gk. tropikos “of or pertaining to a turn or change; of or pertaining to to the turn of the Sun’s apparent motion at solstice,” from trope “a turning.”

Etymology (PE): Hurgard, literally “Sun’s turning,” from hur, → Sun,

• gard “turning, changing,” from gardidan “to turn, to change;” Mid.Pers. vartitan; Av. varət- “to turn, revolve;” Skt. vrt- “to turn, roll,” vartate “it turns round, rolls;” L. vertere “to turn;” O.H.G. werden “to become;” PIE base *wer- “to turn, bend.”