An Etymological Dictionary of Astronomy and Astrophysics

The condition which exists when two waves of the same frequency pass through their maximum and minimum values in a correlated or synchronized way.

Etymology (EN): → in; → phase.

Etymology (PE): Hamfâz, from ham- “together,” → com- + fâz→ phase.

The condition which exists when two waves of the same frequency pass through their maximum and minimum values in a correlated or synchronized way.

Etymology (EN): → in; → phase.

Etymology (PE): Hamfâz, from ham- “together,” → com- + fâz→ phase.

Situated in the natural or original position or place.

Etymology (EN): From L. in, → in-; L. situ, → site.

Etymology (PE): Dar “in,” → in-; jâ, → place.

Situated in the natural or original position or place.

Etymology (EN): From L. in, → in-; L. situ, → site.

Etymology (PE): Dar “in,” → in-; jâ, → place.

1. Prefix meaning “into, in, on, upon, toward, at;” variants im-; il-; ir- by assimilation of -n- with the following consonant. It occurs also sometimes as en, in loans from O.Fr.
   
2. Prefix meaning “not, opposite of, without.”

Etymology (EN): 1) From L. in; cf. Gk. en; P.Gmc. *in (cf. O.Fris, Du., Ger., Goth. in); O.E. in, inne “within.”
2) From L. in- “not,” cognate with Gk. an-; O.Pers./Av. an-, a- “not, without;” Skt. an-, a- “not;” P.Gmc. *un-; O.E. un-.

Etymology (PE): 1) Dar- “in,” from Mid.Pers. andar, → intra-.

2. nâ-, na “not,” ma- “not” (prohibitive); Mid.Pers. nê, ma “no, not;” O.Pers. naiy, nai “not;” Av. nôit, naē “not;” cf. Skt. ná “not;” L. ne-, in-, un-; Gk. ni; Lith. nè; O.C.S. ne “not;” PIE *ne-.
   bi- privative prefix, from Mid.Pers. abi-, O.Pers. *apaiy-, Av. apa-.
   a-, an-, from O.Pers./Av. negation prefix appearing before consonants and vowels respectively.
   A couple of examples in Mod.Pers.: amordâd “immortality, name of the fifth month in the Iranian calendar,” anušé; “fortunate, happy,” anirani “non Iranian,” âhu “vice, defect,” âsoqdé “unburnt, half-burnt wood.”

1. Prefix meaning “into, in, on, upon, toward, at;” variants im-; il-; ir- by assimilation of -n- with the following consonant. It occurs also sometimes as en, in loans from O.Fr.
   
2. Prefix meaning “not, opposite of, without.”

Etymology (EN): 1) From L. in; cf. Gk. en; P.Gmc. *in (cf. O.Fris, Du., Ger., Goth. in); O.E. in, inne “within.”
2) From L. in- “not,” cognate with Gk. an-; O.Pers./Av. an-, a- “not, without;” Skt. an-, a- “not;” P.Gmc. *un-; O.E. un-.

Etymology (PE): 1) Dar- “in,” from Mid.Pers. andar, → intra-.

2. nâ-, na “not,” ma- “not” (prohibitive); Mid.Pers. nê, ma “no, not;” O.Pers. naiy, nai “not;” Av. nôit, naē “not;” cf. Skt. ná “not;” L. ne-, in-, un-; Gk. ni; Lith. nè; O.C.S. ne “not;” PIE *ne-.
   bi- privative prefix, from Mid.Pers. abi-, O.Pers. *apaiy-, Av. apa-.
   a-, an-, from O.Pers./Av. negation prefix appearing before consonants and vowels respectively.
   A couple of examples in Mod.Pers.: amordâd “immortality, name of the fifth month in the Iranian calendar,” anušé; “fortunate, happy,” anirani “non Iranian,” âhu “vice, defect,” âsoqdé “unburnt, half-burnt wood.”

A group to which the speaker, the person spoken of, etc. belongs.

Etymology (EN): → in-; → group.

Etymology (PE): Xodi “insider, familiar, friend,” from xod “own,” → self-.

A group to which the speaker, the person spoken of, etc. belongs.

Etymology (EN): → in-; → group.

Etymology (PE): Xodi “insider, familiar, friend,” from xod “own,” → self-.

The quality or condition of being inaccurate.
The difference between the input quantity applied to a measuring instrument and the output quantity indicated by that instrument. The inaccuracy of an instrument is equal to the sum of its instrument error and its uncertainty.

See also: From negation prefix → in- + → accuracy

The quality or condition of being inaccurate.
The difference between the input quantity applied to a measuring instrument and the output quantity indicated by that instrument. The inaccuracy of an instrument is equal to the sum of its instrument error and its uncertainty.

See also: From negation prefix → in- + → accuracy

1. Not → active.
   

2. Chem.: Not → reactive.

See also: → in-; → active.

1. Not → active.
   

2. Chem.: Not → reactive.

See also: → in-; → active.

State of glowing at high → temperature; white or bright-red → heat.

See also: Quality, state noun from → incandescent.

State of glowing at high → temperature; white or bright-red → heat.

See also: Quality, state noun from → incandescent.

1. (Of light) produced by → incandescence.
   

2. Glowing or → white with → heat.
   

3. Intensely → bright; brilliant (Dictionary.com).

Etymology (EN): From Fr., from L. incandescent-, incandescens, p.p. of incandescere “to become hot,” from → in- + candescere “to become hot,” from candere “to glow.”

Etymology (PE): Foruzandé, agent noun and verbal adj. from foruzidan, → glow.

1. (Of light) produced by → incandescence.
   

2. Glowing or → white with → heat.
   

3. Intensely → bright; brilliant (Dictionary.com).

Etymology (EN): From Fr., from L. incandescent-, incandescens, p.p. of incandescere “to become hot,” from → in- + candescere “to become hot,” from candere “to glow.”

Etymology (PE): Foruzandé, agent noun and verbal adj. from foruzidan, → glow.

Electric lamp in which light is produced by the heating effect of a → metal  → filament.

See also: → incandescent; → lamp.

Electric lamp in which light is produced by the heating effect of a → metal  → filament.

See also: → incandescent; → lamp.

1. The degree, extent, or frequency of occurrence, especially of something unwanted.
   

2. The act of striking a → light ray or → beam of particles on a surface. Also the direction of striking.

Etymology (EN): M.E., from M.Fr. incidence, from L.L. incidentia, from incidere “to happen, befall,” from in- “on” + -cidere, combining form of cadere “to fall,” → case.

Etymology (PE): Fotâd,literally “fall, the act of falling,” from fotâdan “to fall,” variant of oftâdan “to fall; to happen,” → coincide.

1. The degree, extent, or frequency of occurrence, especially of something unwanted.
   

2. The act of striking a → light ray or → beam of particles on a surface. Also the direction of striking.

Etymology (EN): M.E., from M.Fr. incidence, from L.L. incidentia, from incidere “to happen, befall,” from in- “on” + -cidere, combining form of cadere “to fall,” → case.

Etymology (PE): Fotâd,literally “fall, the act of falling,” from fotâdan “to fall,” variant of oftâdan “to fall; to happen,” → coincide.

Same as → angle of incidence.

See also: → incidence; → angle.

Same as → angle of incidence.

See also: → incidence; → angle.

1. An instance of something happening; an event or occurrence.
   

2a) Likely or apt to happen.

2b) Falling or striking on something, as light rays or a beam of particles.

Etymology (EN): → incidence.

Etymology (PE): Fotân, agent noun and adj. from fotâdan, → incidence.

1. An instance of something happening; an event or occurrence.
   

2a) Likely or apt to happen.

2b) Falling or striking on something, as light rays or a beam of particles.

Etymology (EN): → incidence.

Etymology (PE): Fotân, agent noun and adj. from fotâdan, → incidence.

The → light ray that strikes a surface before → reflection, → refraction, or → absorption. Opposite of → emergent ray.

See also: → incident; → ray.

The → light ray that strikes a surface before → reflection, → refraction, or → absorption. Opposite of → emergent ray.

See also: → incident; → ray.

To cut into; to cut marks upon.

Etymology (EN): M.E., from O.Fr. enciser, from L. incisus, p.p. of incidere “to cut into, cut through,” from → in- +
caedere “to cut,” → precise.

Etymology (PE): Darsunidan, from dar, → in- + sun “cut,” → precise.

To cut into; to cut marks upon.

Etymology (EN): M.E., from O.Fr. enciser, from L. incisus, p.p. of incidere “to cut into, cut through,” from → in- +
caedere “to cut,” → precise.

Etymology (PE): Darsunidan, from dar, → in- + sun “cut,” → precise.

The act of incising. A cutting into, especially for surgical purposes.

See also: Verbal noun of → incise.

The act of incising. A cutting into, especially for surgical purposes.

See also: Verbal noun of → incise.

To stir, encourage, or urge on; stimulate or prompt to action (Dictionary.com).

See also: → in-; → excite.

To stir, encourage, or urge on; stimulate or prompt to action (Dictionary.com).

See also: → in-; → excite.

The act of inciting. The state of being incited. motive.

See also: Verbal noun of → incite.

The act of inciting. The state of being incited. motive.

See also: Verbal noun of → incite.

1. The angle between two lines or two planes.
   
2. An orbital element that defines the angle between the orbital plane of a solar system body (planet, comet, asteroid) and the plane of the ecliptic.
   
3. The angle between the equatorial and orbital planes of a planet.

Etymology (EN): Inclination, from M.E. inclinacioun, from L. inclination-, from inclinat(us) p.p. of inclinare, from → in- + clinare “to bend;” cf. Gk. klinein “to cause to slope, slant, incline;” Skt. sri- “to lean,” O.Pers. θray-; Av. sray- “to lean;” Mod.Pers. kil “bent, inclined, slant;” PIE base *klei- “to lean, incline” from which is also derived
P.Gmc. *khlinen (Ger. lehnen, E. lean).

Etymology (PE): Darkil, from prefix dar- “in” + kil “bent, crooked, inclined” [Dehxodâ], Mid.Pers. xwahl “bent, crooked” (Mod.Pers. dialectal/colloquial variants kowleh, cowleh, cowl, caval, xohl, xohal, hol), cf. Skt. kûla- “slope, declivity;” PIE base *klei-, as above.

1. The angle between two lines or two planes.
   
2. An orbital element that defines the angle between the orbital plane of a solar system body (planet, comet, asteroid) and the plane of the ecliptic.
   
3. The angle between the equatorial and orbital planes of a planet.

Etymology (EN): Inclination, from M.E. inclinacioun, from L. inclination-, from inclinat(us) p.p. of inclinare, from → in- + clinare “to bend;” cf. Gk. klinein “to cause to slope, slant, incline;” Skt. sri- “to lean,” O.Pers. θray-; Av. sray- “to lean;” Mod.Pers. kil “bent, inclined, slant;” PIE base *klei- “to lean, incline” from which is also derived
P.Gmc. *khlinen (Ger. lehnen, E. lean).

Etymology (PE): Darkil, from prefix dar- “in” + kil “bent, crooked, inclined” [Dehxodâ], Mid.Pers. xwahl “bent, crooked” (Mod.Pers. dialectal/colloquial variants kowleh, cowleh, cowl, caval, xohl, xohal, hol), cf. Skt. kûla- “slope, declivity;” PIE base *klei-, as above.

The angle between the rotation axis of a planet and the normal to the ecliptic.

See also: → inclination; → axis.

The angle between the rotation axis of a planet and the normal to the ecliptic.

See also: → inclination; → axis.

→ obliquity of the ecliptic.

See also: → inclination; → Earth; → equator.

→ obliquity of the ecliptic.

See also: → inclination; → Earth; → equator.

To deviate from the vertical or horizontal; slant.

See also: Verbal form of → inclination.

To deviate from the vertical or horizontal; slant.

See also: Verbal form of → inclination.

To comprise as a part. See also → conclude, → exclude.

Etymology (EN): From L. includere “to shut in, enclose, imprison, insert,” from → in- “in” + claudere “to shut, close; to block up, make inaccessible,” ultimately from PIE root *klau- “hook, hooked branch or piece of wood; bolt, bar;” cf. L. clavis
“key,” clavus “nail,” claustrum “bar, bolt, barrier;” Gk. kleidos “bar, bolt, key;” O.Ir. clo “nail;” M.Ir. clithar “hedge, fence;” O.C.S. kljuci “hook, key,” kljuciti “shut;” Lith. kliuti “to catch, be caught on;” O.H.G. sliozan “shut,” Ger. schließen “to shut,” Schlüssel “key.”

Etymology (PE): Darkolândan, from dar-, → in-, + kolândan “to shut,” from kolân “wooden bolt, latch;” variants kelân, kolun, kolum, koland, kolandân, kelid, kelidân “wooden bolt, latch;” kalâk “a crook stick for gathering fruit;” (Tabari) kali, (Lori) kelil, (Laki) kalil “key; lock;” (Kurd.) kilil, kilij “key;” (prefixed) biškal(a) “a crooked stick for opening a lock, a sort of key;” (Kurd. Kurmanji) kelemce “handcuff;” (štiyâni) keleku “a large wooden mallet used by bleachers;” (prefixed) eškelak “a piece of wood used between a thief’s fingers to force him confess;” kor-mix, gol-mix “a large-headed peg or stake;” Mid.Pers. kilêl “key.” This family of Pers. words is probably related to PIE root *klau- “hook, hooked branch or piece of wood; bolt, bar,” as above.

To comprise as a part. See also → conclude, → exclude.

Etymology (EN): From L. includere “to shut in, enclose, imprison, insert,” from → in- “in” + claudere “to shut, close; to block up, make inaccessible,” ultimately from PIE root *klau- “hook, hooked branch or piece of wood; bolt, bar;” cf. L. clavis
“key,” clavus “nail,” claustrum “bar, bolt, barrier;” Gk. kleidos “bar, bolt, key;” O.Ir. clo “nail;” M.Ir. clithar “hedge, fence;” O.C.S. kljuci “hook, key,” kljuciti “shut;” Lith. kliuti “to catch, be caught on;” O.H.G. sliozan “shut,” Ger. schließen “to shut,” Schlüssel “key.”

Etymology (PE): Darkolândan, from dar-, → in-, + kolândan “to shut,” from kolân “wooden bolt, latch;” variants kelân, kolun, kolum, koland, kolandân, kelid, kelidân “wooden bolt, latch;” kalâk “a crook stick for gathering fruit;” (Tabari) kali, (Lori) kelil, (Laki) kalil “key; lock;” (Kurd.) kilil, kilij “key;” (prefixed) biškal(a) “a crooked stick for opening a lock, a sort of key;” (Kurd. Kurmanji) kelemce “handcuff;” (štiyâni) keleku “a large wooden mallet used by bleachers;” (prefixed) eškelak “a piece of wood used between a thief’s fingers to force him confess;” kor-mix, gol-mix “a large-headed peg or stake;” Mid.Pers. kilêl “key.” This family of Pers. words is probably related to PIE root *klau- “hook, hooked branch or piece of wood; bolt, bar,” as above.

1. The act of including; the state of being included; that which is included.
   

2. Fragment of foreign material enclosed within the mass of a → mineral or → meteorite. See also → CAI meteorite.

See also: Verbal noun of → include.

1. The act of including; the state of being included; that which is included.
   

2. Fragment of foreign material enclosed within the mass of a → mineral or → meteorite. See also → CAI meteorite.

See also: Verbal noun of → include.

The lack of a fixed phase relationship between two or more waves. → coherent.

See also: Incoherent, from negation prefix → in- + → coherent; → wave.

The lack of a fixed phase relationship between two or more waves. → coherent.

See also: Incoherent, from negation prefix → in- + → coherent; → wave.

1. The condition of two things being so different in nature as to be unable to exist together.
   

   2. Logic: (Of two or more propositions) unable to be true simultaneously.

See also: → incompatible; → -ity.

1. The condition of two things being so different in nature as to be unable to exist together.
   

   2. Logic: (Of two or more propositions) unable to be true simultaneously.

See also: → incompatible; → -ity.

Of two or more propositions, unable to be true simultaneously. → compatible.

Etymology (EN): From M.L. incompatibilis, from → in- “not” + compatibilis (→ compatible).

Etymology (PE): Nâsâzgâr, from nâ- “not,” → in-,

• sâzgâr, → compatible.

Of two or more propositions, unable to be true simultaneously. → compatible.

Etymology (EN): From M.L. incompatibilis, from → in- “not” + compatibilis (→ compatible).

Etymology (PE): Nâsâzgâr, from nâ- “not,” → in-,

• sâzgâr, → compatible.

The state of being incomplete, for example in photometric studies of a population of stars when the faintest members of the population are lacking. → completeness

See also: Negative of → completeness.

The state of being incomplete, for example in photometric studies of a population of stars when the faintest members of the population are lacking. → completeness

See also: Negative of → completeness.

A flow whose volume or density does not change under pressure, and therefore its density is a constant. In other words, an ideal flow in which the → divergence of velocity is zero.
→ compressible flow.

See also: → incompressible, from → in “not” +
→ compressible; → flow.

A flow whose volume or density does not change under pressure, and therefore its density is a constant. In other words, an ideal flow in which the → divergence of velocity is zero.
→ compressible flow.

See also: → incompressible, from → in “not” +
→ compressible; → flow.

1. Lack of consistency or agreement; incompatibility; an inconsistent feature or quality.
   

   2. Logic: The property of being inconsistent; a self-contradictory proposition (TheFreeDictionary.com).

See also: → in-; → consistency.

1. Lack of consistency or agreement; incompatibility; an inconsistent feature or quality.
   

   2. Logic: The property of being inconsistent; a self-contradictory proposition (TheFreeDictionary.com).

See also: → in-; → consistency.

1. Lacking in consistency, agreement, or compatibility; at variance.
   

   2. Containing contradictory elements.
      

   3. Maths: (of two or more equations) not having one common set of values of the variables: x + 2y = 5 and x + 2y = 6 are inconsistent
      

   4. Logic: (of a set of propositions) Enabling an explicit contradiction to be validly derived (TheFreeDictionary.com).

See also: → in-; → consistent.

1. Lacking in consistency, agreement, or compatibility; at variance.
   

   2. Containing contradictory elements.
      

   3. Maths: (of two or more equations) not having one common set of values of the variables: x + 2y = 5 and x + 2y = 6 are inconsistent
      

   4. Logic: (of a set of propositions) Enabling an explicit contradiction to be validly derived (TheFreeDictionary.com).

See also: → in-; → consistent.

1. To make or become greater, in number, size, degree, etc..
   

2. The act of increasing. The amount by which something increases.

Etymology (EN): M.E., from O.Fr. encreiss-, pr.p. stem of encreistre, from L. increscere “to increase, to grow upon,” from → in- “in” + crescere “to grow,” → crescent.

Etymology (PE): Afzudan, from Mid.Pers. abzudan “to increase, grow,” O.Pers. abijav- “to increase, add to, promote,” from abi-, aiby- “in addition to; to; against” + root jav- “press forward,” Av. gav- “to hasten, drive,” Sk. jav- “to press forward, impel quickly, excite,” javate “hastens.”

1. To make or become greater, in number, size, degree, etc..
   

2. The act of increasing. The amount by which something increases.

Etymology (EN): M.E., from O.Fr. encreiss-, pr.p. stem of encreistre, from L. increscere “to increase, to grow upon,” from → in- “in” + crescere “to grow,” → crescent.

Etymology (PE): Afzudan, from Mid.Pers. abzudan “to increase, grow,” O.Pers. abijav- “to increase, add to, promote,” from abi-, aiby- “in addition to; to; against” + root jav- “press forward,” Av. gav- “to hasten, drive,” Sk. jav- “to press forward, impel quickly, excite,” javate “hastens.”

The amount by which a varying quantity increases between two of its stages. In → calculus, the Greek letter Δ (delta) is used to denote an increment; e.g. Δx is an increment of x, contrasted to → decrement.

Etymology (EN): Increment, from L. incrementum “growth, increase,” from stem of increscere “to grow in or upon” from → in- “in” + crescere “to grow.”

Etymology (PE): Fazâyé, from fazâ shortened present stem of afzudan “to add, increase” (Mid.Pers. abzudan “to increase, grow;” O.Pers. abijav- “to increase, add to, promote,” from abi-, aiby- “in addition to; to; against” + root jav- “press forward;” Av. gav- “to hasten, drive;” Skt. jav- “to press forward, impel quickly, excite,” javate “hastens”) + -y- euphonic infix + -é noun/nuance suffix.

The amount by which a varying quantity increases between two of its stages. In → calculus, the Greek letter Δ (delta) is used to denote an increment; e.g. Δx is an increment of x, contrasted to → decrement.

Etymology (EN): Increment, from L. incrementum “growth, increase,” from stem of increscere “to grow in or upon” from → in- “in” + crescere “to grow.”

Etymology (PE): Fazâyé, from fazâ shortened present stem of afzudan “to add, increase” (Mid.Pers. abzudan “to increase, grow;” O.Pers. abijav- “to increase, add to, promote,” from abi-, aiby- “in addition to; to; against” + root jav- “press forward;” Av. gav- “to hasten, drive;” Skt. jav- “to press forward, impel quickly, excite,” javate “hastens”) + -y- euphonic infix + -é noun/nuance suffix.

Not → definite; without fixed or specified limit.

See also: From → in- “not, without” + → definite.

Not → definite; without fixed or specified limit.

See also: From → in- “not, without” + → definite.

Math.: An integral without upper and lower limits. The general antiderivative of
a function. → definite integral.

See also: → definite; → integral.

Math.: An integral without upper and lower limits. The general antiderivative of
a function. → definite integral.

See also: → definite; → integral.

Not dependent.

See also: From negation prefix → in- + → dependent.

Not dependent.

See also: From negation prefix → in- + → dependent.

Statistics: Two events if the occurrence of one of them gives
no → information about whether or not the other event will occur; these events have no influence on each other.

See also: → independent; → event.

Statistics: Two events if the occurrence of one of them gives
no → information about whether or not the other event will occur; these events have no influence on each other.

See also: → independent; → event.

Statistics: Two random variables X and Y
if and only if the value of X has no influence on the value of Y and vice versa.

See also: → dependent; → random; → variable.

Statistics: Two random variables X and Y
if and only if the value of X has no influence on the value of Y and vice versa.

See also: → dependent; → random; → variable.

Math.: A variable whose value determines the value of other variables.
For example, x, in the expression y = f(x), is the independent variable.
See also → dependent variable.

See also: → independent; → variable.

Math.: A variable whose value determines the value of other variables.
For example, x, in the expression y = f(x), is the independent variable.
See also → dependent variable.

See also: → independent; → variable.

Philosophy: The doctrine that there are events which do not correspond with determinism and therefore are uncaused in some sense.
Quantum physics: The claim that the most basic constituents of matter behave indeterministically, in accordance with such properties as the → uncertainty principle.

Etymology (EN): → in-; → determinism.

Etymology (PE): Nâtarmbâvari, nâtarmvari, from nâ- negation prefix

• (â)tarmbâvari, (â)tarmvari, → determinism.

Philosophy: The doctrine that there are events which do not correspond with determinism and therefore are uncaused in some sense.
Quantum physics: The claim that the most basic constituents of matter behave indeterministically, in accordance with such properties as the → uncertainty principle.

Etymology (EN): → in-; → determinism.

Etymology (PE): Nâtarmbâvari, nâtarmvari, from nâ- negation prefix

• (â)tarmbâvari, (â)tarmvari, → determinism.

1. Math.: A number or symbol, often written as a → subscript or → superscript to a mathematical expression, that indicates an operation to be performed, an ordering relation, or a use of the associated expression.
   

2. Physics: A measure of a particular property; e.g. → adiabatic index; → color index; → index of refraction.
   

3. In some → astrolabes, the → rule.
   

4. A sequential arrangement of items, especially in alphabetical or numerical order. → Index Catalogue.

Etymology (EN): Index, from L. index “forefinger, pointer, sign,” literally
“anything which points out,” from indicare “point out, show,” from in- “in” + dicare “to proclaim,” from stem of dicere
“to speak, to say;” PIE base *deik- “to point out” (cf. Av. daēs- " to show;" Skt. dic- “to point out, show;” Gk. deiknynai “to prove;” O.H.G. zeigon; Ger. zeigen “to show;” O.E. teon “to accuse,” tæcan “to teach”).

Etymology (PE): 1) Dišan, from diš-, simple aorist of Av. daēs- “to show,” as above, + suffix -an.
2) Fehrest, from Mid.Pers. payrâstag “arranged,” from payrâstan “to arrange; to adorn” (Mod.Pers. pirâstan); Proto-Ir. *pati-rāsta-, from *pati “to, at, for, in” (cf. Mid.Pers.
pad “to, at, for, in;” Mod.Pers. be, beh;
Old.Pers. paity; Av. paiti “to, toward, in, at;”
Skt. práti; Gk. poti) + *rād- “to direct, arrange”
(cf. Mod.Pers. raj “line, row,” variants raž, rak, râk, rezg (Lori), ris, risé, radé, rasté, râsté, related to râst “right, true; just, upright, straight;” Mid.Pers. râst “true, straight, direct;” Sogdian rəšt “right;” O.Pers. rāsta- “straight, true,” rās- “to be right, straight, true;” Av. rāz- “to direct, put in line, set,” razan- “order;”
cf. Skt. raj- “to direct, stretch,” rjuyant- “walking straight;” Gk. orektos “stretched out;” L. regere “to lead straight, guide, rule,” p.p. rectus “right, straight;” PIE base *reg- “move in a straight line,” hence, “to direct, rule”).

1. Math.: A number or symbol, often written as a → subscript or → superscript to a mathematical expression, that indicates an operation to be performed, an ordering relation, or a use of the associated expression.
   

2. Physics: A measure of a particular property; e.g. → adiabatic index; → color index; → index of refraction.
   

3. In some → astrolabes, the → rule.
   

4. A sequential arrangement of items, especially in alphabetical or numerical order. → Index Catalogue.

Etymology (EN): Index, from L. index “forefinger, pointer, sign,” literally
“anything which points out,” from indicare “point out, show,” from in- “in” + dicare “to proclaim,” from stem of dicere
“to speak, to say;” PIE base *deik- “to point out” (cf. Av. daēs- " to show;" Skt. dic- “to point out, show;” Gk. deiknynai “to prove;” O.H.G. zeigon; Ger. zeigen “to show;” O.E. teon “to accuse,” tæcan “to teach”).

Etymology (PE): 1) Dišan, from diš-, simple aorist of Av. daēs- “to show,” as above, + suffix -an.
2) Fehrest, from Mid.Pers. payrâstag “arranged,” from payrâstan “to arrange; to adorn” (Mod.Pers. pirâstan); Proto-Ir. *pati-rāsta-, from *pati “to, at, for, in” (cf. Mid.Pers.
pad “to, at, for, in;” Mod.Pers. be, beh;
Old.Pers. paity; Av. paiti “to, toward, in, at;”
Skt. práti; Gk. poti) + *rād- “to direct, arrange”
(cf. Mod.Pers. raj “line, row,” variants raž, rak, râk, rezg (Lori), ris, risé, radé, rasté, râsté, related to râst “right, true; just, upright, straight;” Mid.Pers. râst “true, straight, direct;” Sogdian rəšt “right;” O.Pers. rāsta- “straight, true,” rās- “to be right, straight, true;” Av. rāz- “to direct, put in line, set,” razan- “order;”
cf. Skt. raj- “to direct, stretch,” rjuyant- “walking straight;” Gk. orektos “stretched out;” L. regere “to lead straight, guide, rule,” p.p. rectus “right, straight;” PIE base *reg- “move in a straight line,” hence, “to direct, rule”).

Either of two catalogues of non-stellar objects, which serve as supplements to the → New General Catalogue.

See also: → index; → catalog

Either of two catalogues of non-stellar objects, which serve as supplements to the → New General Catalogue.

See also: → index; → catalog

Same as → refractive index.

See also: → index; → refraction.

Same as → refractive index.

See also: → index; → refraction.

The → numeral system consisting of the numerals 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 which evolved into the system we use today. The Indian numerals was a place-value or positional system. The Indians were the first to develop a base 10 positional system. Same as → Hindu-Arabic numeral system.

See also: Indian, from India, → Indus; → numeral; → system.

The → numeral system consisting of the numerals 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 which evolved into the system we use today. The Indian numerals was a place-value or positional system. The Indians were the first to develop a base 10 positional system. Same as → Hindu-Arabic numeral system.

See also: Indian, from India, → Indus; → numeral; → system.

A color between blue and violet.

Etymology (EN): From Sp. indico, Portuguese endego, and Du. (via Portuguese) indigo, from L. indicum “indigo,” from Gk. indikon “blue dye from India,” literally “Indian (substance),” neuter of indikos “Indian,” → Indus.

Etymology (PE): Nil “indigo color; the indigo plant;” Mid.Pers. nil; cf. Skt. nīlī, nīlā “the indigo plant; indigo color.”

A color between blue and violet.

Etymology (EN): From Sp. indico, Portuguese endego, and Du. (via Portuguese) indigo, from L. indicum “indigo,” from Gk. indikon “blue dye from India,” literally “Indian (substance),” neuter of indikos “Indian,” → Indus.

Etymology (PE): Nil “indigo color; the indigo plant;” Mid.Pers. nil; cf. Skt. nīlī, nīlā “the indigo plant; indigo color.”

Not in a direct course, path, action, or procedure.

See also: → in-; → direct.

Not in a direct course, path, action, or procedure.

See also: → in-; → direct.

A word or group of words representing the person or thing with reference to which the action of a verb is performed. In English generally coming between the verb and the direct object and paraphrasable as the object of a preposition, usually to or for, following the direct object, as the boy in He gave the boy a book (Dictionary.com).

See also: → indirect; → object.

A word or group of words representing the person or thing with reference to which the action of a verb is performed. In English generally coming between the verb and the direct object and paraphrasable as the object of a preposition, usually to or for, following the direct object, as the boy in He gave the boy a book (Dictionary.com).

See also: → indirect; → object.

1a) A single human being, as distinguished from a group (Dictionary.com).

1b) A distinct, indivisible entity; a single thing, being, instance, or item
(Dictionary.com).

1c) Logic: An → object or element taken as the → subject of the → predicates of → first-order logic.

2. Of, pertaining to, or characteristic of a particular person or thing. → individual constant, → individual variable.

Etymology (EN): M.E., from M.L. individualis, from L. individuus “indivisible,” from → in- “not, opposite of” + dividuus “divisible,” from dividere, → divide.

Etymology (PE): Takâl, from tak, → single, + suffix -âl, → -al; takâli with adj. suffix -i.

1a) A single human being, as distinguished from a group (Dictionary.com).

1b) A distinct, indivisible entity; a single thing, being, instance, or item
(Dictionary.com).

1c) Logic: An → object or element taken as the → subject of the → predicates of → first-order logic.

2. Of, pertaining to, or characteristic of a particular person or thing. → individual constant, → individual variable.

Etymology (EN): M.E., from M.L. individualis, from L. individuus “indivisible,” from → in- “not, opposite of” + dividuus “divisible,” from dividere, → divide.

Etymology (PE): Takâl, from tak, → single, + suffix -âl, → -al; takâli with adj. suffix -i.

In predicate logic: A → word or → expression that represents a → specific  → individual or → object. A single object can be denoted by multiple individual constants, reflecting the fact that objects can have multiple names. On the other hand, any individual constant can only denote one object. Individual constants are represented by lower case letters from the beginning of the alphabet: a, b, c.

See also: → individual; → constant.

In predicate logic: A → word or → expression that represents a → specific  → individual or → object. A single object can be denoted by multiple individual constants, reflecting the fact that objects can have multiple names. On the other hand, any individual constant can only denote one object. Individual constants are represented by lower case letters from the beginning of the alphabet: a, b, c.

See also: → individual; → constant.

In → predicate logic,
a variable which represents an unspecified → subject. Individual variables work just as do variables in algebra, they stand in for a value, but have no fixed value of their own. They are represented by lower case letters taken from the end of the alphabet x, y, z; and if additional variables are needed by u, v, w, as well.

See also: → individual; → variable.

In → predicate logic,
a variable which represents an unspecified → subject. Individual variables work just as do variables in algebra, they stand in for a value, but have no fixed value of their own. They are represented by lower case letters taken from the end of the alphabet x, y, z; and if additional variables are needed by u, v, w, as well.

See also: → individual; → variable.

1. A social theory advocating the liberty, rights, or independent action of the individual (Dictionary.com).
   

2. An individual peculiarity.

See also: → individual; → -ism.

1. A social theory advocating the liberty, rights, or independent action of the individual (Dictionary.com).
   

2. An individual peculiarity.

See also: → individual; → -ism.

1. A person who shows great independence or individuality in thought or action (Dictionary.com).
   

2. An advocate of → individualism (Dictionary.com).

See also: → individual; → -ist.

1. A person who shows great independence or individuality in thought or action (Dictionary.com).
   

2. An advocate of → individualism (Dictionary.com).

See also: → individual; → -ist.

The particular character, or aggregate of qualities, that distinguishes one person or thing from others (Dictionary.com).

See also: → individual; → -ity.

The particular character, or aggregate of qualities, that distinguishes one person or thing from others (Dictionary.com).

See also: → individual; → -ity.

The process or state of discriminating the individual from the generic group or species.

See also: → individualize; → -tion.

The process or state of discriminating the individual from the generic group or species.

See also: → individualize; → -tion.

To make individual or distinctive; give an individual or distinctive character to (Dictionary.com).

See also: → individual; → -ize.

To make individual or distinctive; give an individual or distinctive character to (Dictionary.com).

See also: → individual; → -ize.

To cause or initiate by influence or some means; e.g. → induced current; → induced emission.

Etymology (EN): Induce, “to lead by persuasions or other influences,” from L. inducere “to lead into, persuade,” from → in- “in”

• ducere “to lead,” from PIE *deuk- “to lead” (cf. O.E. togian “to pull, drag,” O.H.G. ziohan “to pull”).

Etymology (PE): Darhâxtan, darhâzidan, from dar- “in” + Mid.Pers. hâxtan, hâzidan, “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 *sek^w- “to follow.”

To cause or initiate by influence or some means; e.g. → induced current; → induced emission.

Etymology (EN): Induce, “to lead by persuasions or other influences,” from L. inducere “to lead into, persuade,” from → in- “in”

• ducere “to lead,” from PIE *deuk- “to lead” (cf. O.E. togian “to pull, drag,” O.H.G. ziohan “to pull”).

Etymology (PE): Darhâxtan, darhâzidan, from dar- “in” + Mid.Pers. hâxtan, hâzidan, “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 *sek^w- “to follow.”

Brought about or caused by → induction.

See also: Induced, p.p. of → induce.

Brought about or caused by → induction.

See also: Induced, p.p. of → induce.

Current resulting from the relative motion of a conductor through a magnetic field.

See also: → induced ; → current.

Current resulting from the relative motion of a conductor through a magnetic field.

See also: → induced ; → current.

An electric field created by the variation of a magnetic field. The induced electric field lines are usually perpendicular to the changing magnetic field that produces them.

See also: → induced; → electric; → field.

An electric field created by the variation of a magnetic field. The induced electric field lines are usually perpendicular to the changing magnetic field that produces them.

See also: → induced; → electric; → field.

The emission of radiation from an atom when it is bombarded by photons. The induced radiation has the same wavelength and direction as the bombarding radiation. Same as → stimulated emission.

See also: → induced; → emission.

The emission of radiation from an atom when it is bombarded by photons. The induced radiation has the same wavelength and direction as the bombarding radiation. Same as → stimulated emission.

See also: → induced; → emission.

Fission which takes place when a nucleon is bombarded with neutrons or high-energy radiation (gamma rays).

See also: Induced, p.p. of → induce; → fission.

Fission which takes place when a nucleon is bombarded with neutrons or high-energy radiation (gamma rays).

See also: Induced, p.p. of → induce; → fission.

The property of an electric circuit, or of two neighboring circuits, by virtue of which an electromotive force is induced in one circuit by a change of current in either of them.

See also: Inductance, from induct, from L. inductus, p.p. of
→ induce + → -ance.

The property of an electric circuit, or of two neighboring circuits, by virtue of which an electromotive force is induced in one circuit by a change of current in either of them.

See also: Inductance, from induct, from L. inductus, p.p. of
→ induce + → -ance.

1. General: The act of inducing, bringing about, or causing.
   

2. Electromagnetism: A common term for the process by which a body having electric or magnetic properties produces magnetism, an electric charge, or an → electromotive force in a neighboring body without contact. For more details, see → electromagnetic induction; → electrostatic induction; → magnetic induction.
   

3. Math.: A method of mathematical proof typically used to establish that a given statement is true of all natural numbers. It is done by proving that the first statement in the infinite sequence of statements is true, and then proving that if any one statement in the infinite sequence of statements is true, then so is the next one.
   

4. Logic: Any form of reasoning in which the conclusion, though supported by the premises, does not follow from them necessarily. → inductive reasoning.

See also: Verbal noun of → induce.

1. General: The act of inducing, bringing about, or causing.
   

2. Electromagnetism: A common term for the process by which a body having electric or magnetic properties produces magnetism, an electric charge, or an → electromotive force in a neighboring body without contact. For more details, see → electromagnetic induction; → electrostatic induction; → magnetic induction.
   

3. Math.: A method of mathematical proof typically used to establish that a given statement is true of all natural numbers. It is done by proving that the first statement in the infinite sequence of statements is true, and then proving that if any one statement in the infinite sequence of statements is true, then so is the next one.
   

4. Logic: Any form of reasoning in which the conclusion, though supported by the premises, does not follow from them necessarily. → inductive reasoning.

See also: Verbal noun of → induce.

A device for producing high-voltage pulses by means of → electromagnetic induction. It consists of a primary coil of a few turns of wire, wound on an iron core, and insulated from a secondary coil of many turns which surrounds it coaxially. The current in the primary, which is interrupted periodically, sets up a magnetic field, first big, then zero. This changing field induces a large voltage in the secondary.

See also: → induction; → coil.

A device for producing high-voltage pulses by means of → electromagnetic induction. It consists of a primary coil of a few turns of wire, wound on an iron core, and insulated from a secondary coil of many turns which surrounds it coaxially. The current in the primary, which is interrupted periodically, sets up a magnetic field, first big, then zero. This changing field induces a large voltage in the secondary.

See also: → induction; → coil.

In magnetohydrodynamics, an equation that describes the transport of plasma and magnetic field lines over time:
∂B/∂t = ∇ x (v x B) + η∇²B,

where B is the → magnetic induction, v is the plasma velocity, and η = (μσ)^-1 the → magnetic diffusivity. The first term on the right side represents → magnetic advection and the second term → magnetic diffusion.
The induction equation can also be expressed as:
∂B/∂t = -(v.∇)B + (B.∇)v - B(∇.v),

where the terms of the right-hand side stand for advection, stretching, and compression, respectively. Among these terms, net increase of the field can be done only through the stretching and compression.

See also: → induction; → equation.

In magnetohydrodynamics, an equation that describes the transport of plasma and magnetic field lines over time:
∂B/∂t = ∇ x (v x B) + η∇²B,

where B is the → magnetic induction, v is the plasma velocity, and η = (μσ)^-1 the → magnetic diffusivity. The first term on the right side represents → magnetic advection and the second term → magnetic diffusion.
The induction equation can also be expressed as:
∂B/∂t = -(v.∇)B + (B.∇)v - B(∇.v),

where the terms of the right-hand side stand for advection, stretching, and compression, respectively. Among these terms, net increase of the field can be done only through the stretching and compression.

See also: → induction; → equation.

A component of an electromagnetic field which is
the region close to the source (an antenna) where steady-state magnetic and electrostatic forces can be detected. → radiation field.

See also: → induction; → field.

A component of an electromagnetic field which is
the region close to the source (an antenna) where steady-state magnetic and electrostatic forces can be detected. → radiation field.

See also: → induction; → field.

Of, relating to, or using → induction. induction

See also: From induct, → induce, + → -ive.

Of, relating to, or using → induction. induction

See also: From induct, → induce, + → -ive.

Reasoning from detailed facts to general principles.

See also: → deductive; → reasoning.

Reasoning from detailed facts to general principles.

See also: → deductive; → reasoning.

A coil of wire used to introduce inductance into an electric circuit.

See also: Agent noun of → induce.

A coil of wire used to introduce inductance into an electric circuit.

See also: Agent noun of → induce.

The American Indian. A faint, southern constellation (right ascension: 21 hours, declination: -55 degrees), supposed to represent an American native Indian. It was introduced in the 1603 star atlas of Johann Bayer and contains no stars brighter than the third magnitude. Abbreviation: Ind; genitive: Indi.

Etymology (EN): Indus “an Indian,” from L., from Gk. Indos “the Indus River, an Indian.”

Etymology (PE): Sorxpust “red skin,” the term coming from the reddish skin color of some native Americans, from sorx, → red, + pust “skin,” from Mid.Pers. pôst “skin;” Av. pastô-, in pastô.fraθanhəm “of the breadth of the skin.”
Hendi “Indian,” Mid.Pers. Hindûk, from Hind “Indian;” O.Pers. hindu- “Sind, a province of the Persian Empire on the upper Indus River,” Hinduya- “man of Sind;” Av. hindu-, həndu-; Skt. sindhu- “stream; the Indus; country around the Indus.”

The American Indian. A faint, southern constellation (right ascension: 21 hours, declination: -55 degrees), supposed to represent an American native Indian. It was introduced in the 1603 star atlas of Johann Bayer and contains no stars brighter than the third magnitude. Abbreviation: Ind; genitive: Indi.

Etymology (EN): Indus “an Indian,” from L., from Gk. Indos “the Indus River, an Indian.”

Etymology (PE): Sorxpust “red skin,” the term coming from the reddish skin color of some native Americans, from sorx, → red, + pust “skin,” from Mid.Pers. pôst “skin;” Av. pastô-, in pastô.fraθanhəm “of the breadth of the skin.”
Hendi “Indian,” Mid.Pers. Hindûk, from Hind “Indian;” O.Pers. hindu- “Sind, a province of the Persian Empire on the upper Indus River,” Hinduya- “man of Sind;” Av. hindu-, həndu-; Skt. sindhu- “stream; the Indus; country around the Indus.”

A collision between bodies in which there is a loss of total kinetic energy.

See also: → inelastic; → collision.

A collision between bodies in which there is a loss of total kinetic energy.

See also: → inelastic; → collision.

A type of scattering when the → scattered radiation has a → wavelength different from that of the → incident radiation (→ Raman scattering, → fluorescence ).

See also: → inelastic; → scattering.

A type of scattering when the → scattered radiation has a → wavelength different from that of the → incident radiation (→ Raman scattering, → fluorescence ).

See also: → inelastic; → scattering.

1. A statement of the form a ≠ b, a > b, or a < b, asserting one quantity is greater than or less than another quantity. → equality.
   
2. An irregularity in the movement of a celestial object in its orbit about another which cannot be explained by their mutual gravitational attraction. Irregularities are often due to perturbation by other neighboring objects.

See also: → in-; → equality.

1. A statement of the form a ≠ b, a > b, or a < b, asserting one quantity is greater than or less than another quantity. → equality.
   
2. An irregularity in the movement of a celestial object in its orbit about another which cannot be explained by their mutual gravitational attraction. Irregularities are often due to perturbation by other neighboring objects.

See also: → in-; → equality.

Having no inherent power of action, motion, or resistance (opposed to active).
Chemistry: A chemically inactive element, compound or material. → inert gas.

Etymology (EN): Inert, from Fr. inerte, from L. inertem “unskilled, inactive,” from → in- “without” + ars (gen. artis) “skill.”

Etymology (PE): Laxt “sluggish, inert.”

Having no inherent power of action, motion, or resistance (opposed to active).
Chemistry: A chemically inactive element, compound or material. → inert gas.

Etymology (EN): Inert, from Fr. inerte, from L. inertem “unskilled, inactive,” from → in- “without” + ars (gen. artis) “skill.”

Etymology (PE): Laxt “sluggish, inert.”

Any one of six gases helium, neon, argon, krypton, xenon, and radon, all of whose atomic shells contain complete numbers of electrons so that the atoms are almost completely chemically inactive. Same as noble gases.

See also: → inert; → gas.

Any one of six gases helium, neon, argon, krypton, xenon, and radon, all of whose atomic shells contain complete numbers of electrons so that the atoms are almost completely chemically inactive. Same as noble gases.

See also: → inert; → gas.

Tendency of a body to preserve its state of rest or uniform motion in a straight line.

Etymology (EN): Inertia, from L. inertia “un-skillfulness, idleness,” from iners (gen. inertis) “unskilled, inactive;” → inert.

Etymology (PE): Laxti “sluggishness, inertia.”

Tendency of a body to preserve its state of rest or uniform motion in a straight line.

Etymology (EN): Inertia, from L. inertia “un-skillfulness, idleness,” from iners (gen. inertis) “unskilled, inactive;” → inert.

Etymology (PE): Laxti “sluggishness, inertia.”

An ellipsoid used in describing the motion of a rotating rigid body. It is stationary with respect to the rotating body, and is determined by the body’s moments of inertia.

See also: → ellipsoid; → inertia.

An ellipsoid used in describing the motion of a rotating rigid body. It is stationary with respect to the rotating body, and is determined by the body’s moments of inertia.

See also: → ellipsoid; → inertia.

Of or relating to inertia.

Etymology (EN): From → inertia + → -al.

Etymology (PE): Laxt, adj. of laxti, → inertia

Of or relating to inertia.

Etymology (EN): From → inertia + → -al.

Etymology (PE): Laxt, adj. of laxti, → inertia

A force arising from the → acceleration of an observer’s → frame of reference.

See also: → inertial; → force.

A force arising from the → acceleration of an observer’s → frame of reference.

See also: → inertial; → force.

→ inertial reference frame.

See also: → inertial; → frame.

→ inertial reference frame.

See also: → inertial; → frame.

The mass of a body as determined from the acceleration of the body when it is subjected to a force that is not due to gravity.

See also: → inertial; → mass.

The mass of a body as determined from the acceleration of the body when it is subjected to a force that is not due to gravity.

See also: → inertial; → mass.

Motion free of any force, with constant velocity.

See also: → inertial; → motion.

Motion free of any force, with constant velocity.

See also: → inertial; → motion.

1. A periodic motion of a particle that moves, free from external forces, over the surface of a rotating sphere, such the Earth. Inertial oscillations result from the → Coriolis force. For example, a hockey puck launched on a big enough lake in the northern hemisphere would turn to the right (east) and eventually loop back to nearly the initial point (actually west of that point). The time it takes for the huckey puck to return can be computed with the → Coriolis frequency.
   

2. Meteo.: An anticyclonic (clockwise) rotation in the northern hemisphere, with the Coriolis force providing the → centripetal acceleration with period of 2π/f, where f is the Coriolis frequency. The opposite should occur in the southern hemisphere.

See also: → inertial; → oscillation.

1. A periodic motion of a particle that moves, free from external forces, over the surface of a rotating sphere, such the Earth. Inertial oscillations result from the → Coriolis force. For example, a hockey puck launched on a big enough lake in the northern hemisphere would turn to the right (east) and eventually loop back to nearly the initial point (actually west of that point). The time it takes for the huckey puck to return can be computed with the → Coriolis frequency.
   

2. Meteo.: An anticyclonic (clockwise) rotation in the northern hemisphere, with the Coriolis force providing the → centripetal acceleration with period of 2π/f, where f is the Coriolis frequency. The opposite should occur in the southern hemisphere.

See also: → inertial; → oscillation.

A → reference frame or coordinate system in which there are no accelerations, only zero or uniform motion in a straight line. According to the special theory of relativity, it is impossible to distinguish between such frames by means of any internal measurement.

See also: → inertial; → reference; → frame.

A → reference frame or coordinate system in which there are no accelerations, only zero or uniform motion in a straight line. According to the special theory of relativity, it is impossible to distinguish between such frames by means of any internal measurement.

See also: → inertial; → reference; → frame.

The fall of matter toward the center of a region of gravitational influence.

Etymology (EN): Infall, from → in- + → fall.

Etymology (PE): Darun-oft, from darun- “in, into; within” (Mid.Pers. andarôn
“inside,” from andar, → inter-, + rôn “side, direction;” Av. ravan- “(course of a) river”)

• oft, → fall.

The fall of matter toward the center of a region of gravitational influence.

Etymology (EN): Infall, from → in- + → fall.

Etymology (PE): Darun-oft, from darun- “in, into; within” (Mid.Pers. andarôn
“inside,” from andar, → inter-, + rôn “side, direction;” Av. ravan- “(course of a) river”)

• oft, → fall.

To affect, cause infection, or contaminate with a pathogenic microorganism or agent.

Etymology (EN): M.E. infecten, from L. infectus, p.p. of inficere “to immerse in dye, discolor, taint, poison,” from equivalent to → in- + → -fac, combining form of facere “to do, make,” → fact, + -tus p.p. suffix; from PIE root *dhe- “to set, put.”

Etymology (PE): Fažidan, infinitive from faž “dirt, filth, pus;” related word faže, fažnâk, fažgen, fažegen, fažgin, fažqand “filthy, dirty;” of unknown origin. It may be related to Proto-Ir. root *xard- “to defecate,” with offshoots xard “muddy place,” xarra “mud,” (+ *pati-) payxâl “excrement.”

To affect, cause infection, or contaminate with a pathogenic microorganism or agent.

Etymology (EN): M.E. infecten, from L. infectus, p.p. of inficere “to immerse in dye, discolor, taint, poison,” from equivalent to → in- + → -fac, combining form of facere “to do, make,” → fact, + -tus p.p. suffix; from PIE root *dhe- “to set, put.”

Etymology (PE): Fažidan, infinitive from faž “dirt, filth, pus;” related word faže, fažnâk, fažgen, fažegen, fažgin, fažqand “filthy, dirty;” of unknown origin. It may be related to Proto-Ir. root *xard- “to defecate,” with offshoots xard “muddy place,” xarra “mud,” (+ *pati-) payxâl “excrement.”

1. A thing that infects or causes infection.
   

   2. Causing infection; infecting.

See also: → infect; → -ant.

1. A thing that infects or causes infection.
   

   2. Causing infection; infecting.

See also: → infect; → -ant.

1. Affected with a disease-causing organism.
   

   2. Computers: Affected with a → virus.

See also: P. p. of → infect.

1. Affected with a disease-causing organism.
   

   2. Computers: Affected with a → virus.

See also: P. p. of → infect.

A branch of medicine that deals with the diagnosis, management and treatment of various infectious or contagious diseases.

See also: → infection; → -logy.

A branch of medicine that deals with the diagnosis, management and treatment of various infectious or contagious diseases.

See also: → infection; → -logy.

1. An act or fact of infecting; state of being infected.
   

   2. An infecting agency or influence.
      

   3. An infectious disease.
      

   4. Computers: The presence of a virus in, or its introduction into, a computer system.

See also: Verbal noun of → infect.

1. An act or fact of infecting; state of being infected.
   

   2. An infecting agency or influence.
      

   3. An infectious disease.
      

   4. Computers: The presence of a virus in, or its introduction into, a computer system.

See also: Verbal noun of → infect.

1. Capable of causing infection.
   

2. Caused by or capable of being transmitted by infection.

See also: → infect(ion) + -ious, variant of → -ous.

1. Capable of causing infection.
   

2. Caused by or capable of being transmitted by infection.

See also: → infect(ion) + -ious, variant of → -ous.

Capable of causing infection.

See also: → infect; → -ive.

Capable of causing infection.

See also: → infect; → -ive.

1. The act or process of deriving logical conclusions from premises known or assumed to be true.
   
2. Something that is inferred.

Etymology (EN): From M.L. inferentia, from inferre, from → in- “in” + ferre “to carry, bear,” cognate with Pers. bordan “to carry, bear,” as below.

Etymology (PE): Darbord (on the models of daryâft “perception” and peybord “understanding, finding;” see also bâzbord, → reference), from dar-, → in-,

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

1. The act or process of deriving logical conclusions from premises known or assumed to be true.
   
2. Something that is inferred.

Etymology (EN): From M.L. inferentia, from inferre, from → in- “in” + ferre “to carry, bear,” cognate with Pers. bordan “to carry, bear,” as below.

Etymology (PE): Darbord (on the models of daryâft “perception” and peybord “understanding, finding;” see also bâzbord, → reference), from dar-, → in-,

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

Lower in place or position; closer to the bottom or base.
Astro.: → inferior conjunction;
→ inferior culmination; → inferior planet.

Etymology (EN): From L. inferior “lower,” comp. form of inferus (adj.) “that is below or beneath,” from infra “below” (→ infrared), cognate with Pers. zir, as below.

Etymology (PE): Zirin, adj. from zir “below, down,” Mid.Pers. azêr “below, under,” êr “below, down; low, under,” adar “low;”
Av. aδara- (adj.), aδairi- (prep.) “below;” cf. Skt. ádhara- “lower;” L. infra (adv., prep.) “below, underneath, beneath,” inferus “lower;” O.E. under “under, among”);
PIE base *ndher.

Lower in place or position; closer to the bottom or base.
Astro.: → inferior conjunction;
→ inferior culmination; → inferior planet.

Etymology (EN): From L. inferior “lower,” comp. form of inferus (adj.) “that is below or beneath,” from infra “below” (→ infrared), cognate with Pers. zir, as below.

Etymology (PE): Zirin, adj. from zir “below, down,” Mid.Pers. azêr “below, under,” êr “below, down; low, under,” adar “low;”
Av. aδara- (adj.), aδairi- (prep.) “below;” cf. Skt. ádhara- “lower;” L. infra (adv., prep.) “below, underneath, beneath,” inferus “lower;” O.E. under “under, among”);
PIE base *ndher.

The conjunction of an inferior planet with the Sun when the planet is between the Sun and the Earth. → superior conjunction.

See also: → inferior; → conjunction.

The conjunction of an inferior planet with the Sun when the planet is between the Sun and the Earth. → superior conjunction.

See also: → inferior; → conjunction.

The meridian transit of a star between the celestial pole and the north point of the horizon. Same as → lower culmination. → superior culmination.

See also: → inferior; → culmination.

The meridian transit of a star between the celestial pole and the north point of the horizon. Same as → lower culmination. → superior culmination.

See also: → inferior; → culmination.

A planet that orbits between the Earth and the Sun. Mercury and Venus are the only two inferior planets in the Solar System.

See also: → inferior; → planète.

A planet that orbits between the Earth and the Sun. Mercury and Venus are the only two inferior planets in the Solar System.

See also: → inferior; → planète.

Unlimited or unmeasurable in extent of space, duration of time, etc.
Math.: Not finite; an infinite quantity or magnitude; large beyond bound.
Of a set, having elements that can be put into one-to-one correspondence with a subset that is not the given set.

See also: → in- + → finite.

Unlimited or unmeasurable in extent of space, duration of time, etc.
Math.: Not finite; an infinite quantity or magnitude; large beyond bound.
Of a set, having elements that can be put into one-to-one correspondence with a subset that is not the given set.

See also: → in- + → finite.

A → statistical population consisting of individuals or items which either possesses the infinite property through some limiting process or is non-enumerable. For example, the population of all → real numbers between 0 and 1 and the population of all → integers are examples of infinite population. In case of random sampling with replacement, any population is always infinite.

See also: → infinite; → population.

A → statistical population consisting of individuals or items which either possesses the infinite property through some limiting process or is non-enumerable. For example, the population of all → real numbers between 0 and 1 and the population of all → integers are examples of infinite population. In case of random sampling with replacement, any population is always infinite.

See also: → infinite; → population.

A series with infinitely many terms, in other words a series that has no last term, such as 1 + 1/4 + 1/9 + 1/16 + · · · + 1/n² + … .

The idea of infinite series is familiar from decimal expansions, for instance the expansion π = 3.14159265358979… can be written as π = 3 + 1/10 + 4/10² + 1/10³ + 5/10⁴ + 9/10⁵ + 2/10⁶ + 6/10⁷ + 5/10⁸ + 3/10⁹ + 5/10¹⁰ + 8/10¹¹ + … , so π is an “infinite sum” of fractions. See also → finite series.

See also: → infinite; → series.

A series with infinitely many terms, in other words a series that has no last term, such as 1 + 1/4 + 1/9 + 1/16 + · · · + 1/n² + … .

The idea of infinite series is familiar from decimal expansions, for instance the expansion π = 3.14159265358979… can be written as π = 3 + 1/10 + 4/10² + 1/10³ + 5/10⁴ + 9/10⁵ + 2/10⁶ + 6/10⁷ + 5/10⁸ + 3/10⁹ + 5/10¹⁰ + 8/10¹¹ + … , so π is an “infinite sum” of fractions. See also → finite series.

See also: → infinite; → series.

A set which can be put in a one-to-one correspondence with part of itself.

Etymology (PE): → infinite; → set.

A set which can be put in a one-to-one correspondence with part of itself.

Etymology (PE): → infinite; → set.

General: Indefinitely or exceedingly small.
Math.: A variable that approaches zero as a limit. A quantity decreasing indefinitely without actually becoming zero.

Etymology (EN): Infinitesimal, coined by Ger. philosopher and mathematician Baron Gottfried Wilhelm von Leibniz (1646-1716) from N.L. infinitesim(us) “infinite in rank,” from infinit(us), → infinite, + -esimus suffix of ordinal numerals + → -al.

Etymology (PE): Bikarânxord, from bikarân “unbounded, unlimited, infinite,”
from bi- “without” + karân “boundary, side, end” (variants karâné, kenâr, from Mid.Pers. karân, karânak, kenâr “edge, limit, boundary,” Av. karana- “side, boundary, end”)

• xord “minute, little, small” (from Mid.Pers. xvart, xôrt “small, insignificant;” Av. ādra- “weak, dependent;” Skt. ādhrá- “small, weak, poor,” nādh “to be oppressed;” Gk. nothros “sluggish;” PIE base *nhdhro-).

General: Indefinitely or exceedingly small.
Math.: A variable that approaches zero as a limit. A quantity decreasing indefinitely without actually becoming zero.

Etymology (EN): Infinitesimal, coined by Ger. philosopher and mathematician Baron Gottfried Wilhelm von Leibniz (1646-1716) from N.L. infinitesim(us) “infinite in rank,” from infinit(us), → infinite, + -esimus suffix of ordinal numerals + → -al.

Etymology (PE): Bikarânxord, from bikarân “unbounded, unlimited, infinite,”
from bi- “without” + karân “boundary, side, end” (variants karâné, kenâr, from Mid.Pers. karân, karânak, kenâr “edge, limit, boundary,” Av. karana- “side, boundary, end”)

• xord “minute, little, small” (from Mid.Pers. xvart, xôrt “small, insignificant;” Av. ādra- “weak, dependent;” Skt. ādhrá- “small, weak, poor,” nādh “to be oppressed;” Gk. nothros “sluggish;” PIE base *nhdhro-).

The body of rules and processes by means of which continuously varying magnitudes are dealt with in → calculus. The combined methods of mathematical analysis of → differential calculus and → integral calculus.

See also: → infinitesimal, → calculus.

The body of rules and processes by means of which continuously varying magnitudes are dealt with in → calculus. The combined methods of mathematical analysis of → differential calculus and → integral calculus.

See also: → infinitesimal, → calculus.

The nominal form of the verb which expresses the idea of action or state without indicating person, number, or tense.

Etymology (EN): Contraction of L. infinitivus modus “unlimited, indefinite mood,” from L. infinitus, → infinite.

Etymology (PE): Karpâyé, literally “action base,” from kar-, → verb, + pâyé, → base.

The nominal form of the verb which expresses the idea of action or state without indicating person, number, or tense.

Etymology (EN): Contraction of L. infinitivus modus “unlimited, indefinite mood,” from L. infinitus, → infinite.

Etymology (PE): Karpâyé, literally “action base,” from kar-, → verb, + pâyé, → base.

That quantity which is greater than any assignable quantity.

See also: Noun form of → infinite.

That quantity which is greater than any assignable quantity.

See also: Noun form of → infinite.

1. Feeble or weak in body or health, especially because of age.
   

2. To unvalidate.

Etymology (EN): M.E. infirm, from L. infirmus “weak, frail, not strong or firm” from → in- “not, opposite of” + firmus, → firm.

Etymology (PE): Nâdeš, from nâ- “not,” → in-, + deš, → firm.

1. Feeble or weak in body or health, especially because of age.
   

2. To unvalidate.

Etymology (EN): M.E. infirm, from L. infirmus “weak, frail, not strong or firm” from → in- “not, opposite of” + firmus, → firm.

Etymology (PE): Nâdeš, from nâ- “not,” → in-, + deš, → firm.

An → affix that is inserted within a root or stem.

Etymology (EN): From L. infixus p.p. of infigere “to fasten in,” from in-

• figere “fasten.”

Etymology (PE): Darvand, from dar- “in” + vand, → affix.

An → affix that is inserted within a root or stem.

Etymology (EN): From L. infixus p.p. of infigere “to fasten in,” from in-

• figere “fasten.”

Etymology (PE): Darvand, from dar- “in” + vand, → affix.

To become inflated; to increase, especially suddenly and substantially. → inflation, → inflatory model.

Etymology (EN): Inflate, from L. inflatus p.p. of inflare “to blow into, puff up,” from → in- “into” + flare “to blow.”

Etymology (PE): Pandâmidan “to swell,” from pandâm [Mo’in] “swelling;” Borujerdi panâm, panam “swellig;” Malâyeri panomidan “to swell;” Laki penamiyen “to swell;” Hamadâni pandumidan “swelling of the eye or other parts of the body;” Kermâni padum kerdan “to swell,” padum “swelled; fat, corpulent;” Tâleši pandâm, pandom “swelling;” Gilaki pandâm kudan “rising of river water caused by flood;” cf. Gk. pneuma “wind; breath,” from pnein “to blow; to breathe;” PIE base *pneu- “to breathe.” Related terms in other Indo-European languages: O.E. fnaeran “to breathe heavily,” fneosan “to snort, sneeze;”
M.H.G. pfnusen, pfnehen “to breathe, pant, sniff, snort, sneeze;” Norw. fnysa “to breeze;” M.Du. fniesen, Du. fniezen “to sneeze;”
O.H.G. niosan, Ger. niesen “to sneeze.”

To become inflated; to increase, especially suddenly and substantially. → inflation, → inflatory model.

Etymology (EN): Inflate, from L. inflatus p.p. of inflare “to blow into, puff up,” from → in- “into” + flare “to blow.”

Etymology (PE): Pandâmidan “to swell,” from pandâm [Mo’in] “swelling;” Borujerdi panâm, panam “swellig;” Malâyeri panomidan “to swell;” Laki penamiyen “to swell;” Hamadâni pandumidan “swelling of the eye or other parts of the body;” Kermâni padum kerdan “to swell,” padum “swelled; fat, corpulent;” Tâleši pandâm, pandom “swelling;” Gilaki pandâm kudan “rising of river water caused by flood;” cf. Gk. pneuma “wind; breath,” from pnein “to blow; to breathe;” PIE base *pneu- “to breathe.” Related terms in other Indo-European languages: O.E. fnaeran “to breathe heavily,” fneosan “to snort, sneeze;”
M.H.G. pfnusen, pfnehen “to breathe, pant, sniff, snort, sneeze;” Norw. fnysa “to breeze;” M.Du. fniesen, Du. fniezen “to sneeze;”
O.H.G. niosan, Ger. niesen “to sneeze.”

1. General: The act of inflating; the state of being inflated.
   

2. Cosmology: A brief exponential expansion of the Universe postulated to have occurred 10^-35 seconds after the → Big Bang, in response to the separation of the → strong interaction from the → electroweak interaction. This idea aims at explaining the → flatness problem, the → horizon problem, and the → magnetic monopole problem. See also → inflaton field.

See also: Verbal noun of → inflate.

1. General: The act of inflating; the state of being inflated.
   

2. Cosmology: A brief exponential expansion of the Universe postulated to have occurred 10^-35 seconds after the → Big Bang, in response to the separation of the → strong interaction from the → electroweak interaction. This idea aims at explaining the → flatness problem, the → horizon problem, and the → magnetic monopole problem. See also → inflaton field.

See also: Verbal noun of → inflate.

A class of → Big Bang models of the Universe that include a finite period of accelerated expansion in their early histories. Such an event would have released enormous energy, stored until then in the vacuum of space-time. The horizon of the Universe expanded, temporarily, much faster than the speed of light.
→ inflaton field.

See also: Inflationary, adj. of → inflation; → model.

A class of → Big Bang models of the Universe that include a finite period of accelerated expansion in their early histories. Such an event would have released enormous energy, stored until then in the vacuum of space-time. The horizon of the Universe expanded, temporarily, much faster than the speed of light.
→ inflaton field.

See also: Inflationary, adj. of → inflation; → model.

The hypothetical → particle that mediates the hypothetical → inflaton field.

See also: From inflat-, from → inflaton field, + particle suffix → -on.

The hypothetical → particle that mediates the hypothetical → inflaton field.

See also: From inflat-, from → inflaton field, + particle suffix → -on.

A hypothetical → scalar field that provides a theoretical basis for → inflation in the early → Big Bang history of the → Universe. The inflaton field would fill space with the same energy at every point. In general, the scalar field can vary with time and space, though to a first approximation everywhere in the Universe will have the same value at any time. The field has a particle associated with it, called → inflaton, just as the → electromagnetic field is associated with the → photon. The inflaton field is characterized also by a → negative pressure that would yield a tremendous → repulsive gravity during a brief lapse of time. In the earliest moments of the Universe, space is uniformly filled with an inflaton field, whose value places it higher up on its → potential energy curve. The inflaton’s → potential energy would drop
in a tiny fraction of a second, on the order of 10^-35 seconds. And yet, during that brief instant, space would expand by a colossal factor, of at least 10³⁰.

See also: → inflaton; → field.

A hypothetical → scalar field that provides a theoretical basis for → inflation in the early → Big Bang history of the → Universe. The inflaton field would fill space with the same energy at every point. In general, the scalar field can vary with time and space, though to a first approximation everywhere in the Universe will have the same value at any time. The field has a particle associated with it, called → inflaton, just as the → electromagnetic field is associated with the → photon. The inflaton field is characterized also by a → negative pressure that would yield a tremendous → repulsive gravity during a brief lapse of time. In the earliest moments of the Universe, space is uniformly filled with an inflaton field, whose value places it higher up on its → potential energy curve. The inflaton’s → potential energy would drop
in a tiny fraction of a second, on the order of 10^-35 seconds. And yet, during that brief instant, space would expand by a colossal factor, of at least 10³⁰.

See also: → inflaton; → field.

1. General: To bend in, to turn from a direct line or course.
   
2. Grammar: To change the ending or form of a word in accordance with other words in a sentence. To apply → inflection to.

Etymology (EN): From M.E. inflecten, from L. inflectere “to bend in, bow, curve,” figuratively, “to change,” from → in- + flectere “to bend, to curve,” of uncertain origin.

Etymology (PE): Darcaftidan, from dar-, → in-, + caftidan, → flex.

1. General: To bend in, to turn from a direct line or course.
   
2. Grammar: To change the ending or form of a word in accordance with other words in a sentence. To apply → inflection to.

Etymology (EN): From M.E. inflecten, from L. inflectere “to bend in, bow, curve,” figuratively, “to change,” from → in- + flectere “to bend, to curve,” of uncertain origin.

Etymology (PE): Darcaftidan, from dar-, → in-, + caftidan, → flex.

A change in the form of a word to indicate a change in such grammatical features as tense, person, gender, case, number, voice, or mood. A general term for → declension and → conjugation.

See also: Verbal noun of → inflect.

A change in the form of a word to indicate a change in such grammatical features as tense, person, gender, case, number, voice, or mood. A general term for → declension and → conjugation.

See also: Verbal noun of → inflect.

A point on a → curve at which the → tangent changes direction, from rotating in one sense to rotating in the opposite sense.

See also: → inflection; → point.

A point on a → curve at which the → tangent changes direction, from rotating in one sense to rotating in the opposite sense.

See also: → inflection; → point.

Of, relating to, or characterized by the use of → inflection, e.g.
→ inflectional affix.

See also: → inflection + → -al.

Of, relating to, or characterized by the use of → inflection, e.g.
→ inflectional affix.

See also: → inflection + → -al.

An → inflection that is added at the end of a root word. In English there are eight inflectional affixes, which are all suffixes. They always follow derivational suffixes and do not change the category of a word.

See also: → inflectional + → affix.

An → inflection that is added at the end of a root word. In English there are eight inflectional affixes, which are all suffixes. They always follow derivational suffixes and do not change the category of a word.

See also: → inflectional + → affix.

1. The act or process of flowing in or into. Something that flows in or into. Opposite of → outflow.
   

2. Meteo: Flow of water into a stream, lake, reservoir, container, basin, aquifer system, etc.

See also: Inflow, from → in- + → flow.

1. The act or process of flowing in or into. Something that flows in or into. Opposite of → outflow.
   

2. Meteo: Flow of water into a stream, lake, reservoir, container, basin, aquifer system, etc.

See also: Inflow, from → in- + → flow.

1. The act or power of producing an → effect, especially inconspicuously; the effect of power exerted.
   

2. To have or exert influence on; affect.

Etymology (EN): M.E., from O.Fr. influence, from L. influentia “stellar emanation” (it was thought an ethereal liquid flowed from the stars and affected the destiny of humans), also “a flow of water,
a flowing in,” from L. influentem (nominative influens), pr.p. of influere “to flow into,” from → in- “into, in, on, upon” + fluere “to flow;” PIE base *bhleu- “to swell, overflow;” cf. Gk. phluein “to boil over, bubble up,” phlein “to abound.”

Etymology (PE): Hanâyeš “influence” (Borhân-e Qâte’; Kasravi). We suggest the following origin
for this word: ultimately from Proto-Ir. *ha-nai “to conduct, direct, guide, lead,”
from *ham-naiH-, from prefix *ham- “together,” also an intensive prefix, → com-, + *naiH- “to lead, conduct, guide;” cf. Av. naii- (naŷ-) “to lead, guide,” naiieiti “leads;”
O.Pers. nay- “to lead, bring” anaya “leads;” Mid.Pers. nidan, ônidan, nay- “to lead, bring;” Sogd. n’y- “to lead;” Choresmian (prefixed, + *apa-) bny- “to remove;” Skt. nī- “to lead,” náyati “leads.”
In dialects: Anâraki niye “to bring, lead;” Kurd. (prefixed) ânin, inân, (with prefix ham-) hânin, hênân “to bring, lead to,” Tâleši ânân, ânoe “to bring together two edges;” Zazaki ân- “to bring;” Qohrudi hunda, hun- “to bring, lead;”
Târi niya-, neg- “to lead;” Lasgardi (prefixed) bin- “to bring, carry;” Qomi niyé, Tafreši neyé “a jab or poke used for leading the cattle;” see also → relate.

1. The act or power of producing an → effect, especially inconspicuously; the effect of power exerted.
   

2. To have or exert influence on; affect.

Etymology (EN): M.E., from O.Fr. influence, from L. influentia “stellar emanation” (it was thought an ethereal liquid flowed from the stars and affected the destiny of humans), also “a flow of water,
a flowing in,” from L. influentem (nominative influens), pr.p. of influere “to flow into,” from → in- “into, in, on, upon” + fluere “to flow;” PIE base *bhleu- “to swell, overflow;” cf. Gk. phluein “to boil over, bubble up,” phlein “to abound.”

Etymology (PE): Hanâyeš “influence” (Borhân-e Qâte’; Kasravi). We suggest the following origin
for this word: ultimately from Proto-Ir. *ha-nai “to conduct, direct, guide, lead,”
from *ham-naiH-, from prefix *ham- “together,” also an intensive prefix, → com-, + *naiH- “to lead, conduct, guide;” cf. Av. naii- (naŷ-) “to lead, guide,” naiieiti “leads;”
O.Pers. nay- “to lead, bring” anaya “leads;” Mid.Pers. nidan, ônidan, nay- “to lead, bring;” Sogd. n’y- “to lead;” Choresmian (prefixed, + *apa-) bny- “to remove;” Skt. nī- “to lead,” náyati “leads.”
In dialects: Anâraki niye “to bring, lead;” Kurd. (prefixed) ânin, inân, (with prefix ham-) hânin, hênân “to bring, lead to,” Tâleši ânân, ânoe “to bring together two edges;” Zazaki ân- “to bring;” Qohrudi hunda, hun- “to bring, lead;”
Târi niya-, neg- “to lead;” Lasgardi (prefixed) bin- “to bring, carry;” Qomi niyé, Tafreši neyé “a jab or poke used for leading the cattle;” see also → relate.

1. To impart → knowledge of a fact or circumstance.
   

2. To supply (oneself) with knowledge of a matter or subject (dictionary.com).
   

3. To convey → information.
   

See also: → informatics, → information theory.

Etymology (EN): Inform, from M.E. informen, from O.Fr. enformer, from L. informare “to shape, form; to form an idea of,” from → in- “into” + → forma “form.”

Etymology (PE): Azdâyidan, from Mid.Pers. azdênidan “to inform,” from azd “information, proclamation; known” (loaned into Arm. azd), from O.Pers. azdā “known,” azdā kar “to become known;” Av. azdā “known;” Sogdian ‘zd’ “informed, known;” cf. Skt. addhā’ “manifestly; certainly, truly,” addhāti “sage.”

1. To impart → knowledge of a fact or circumstance.
   

2. To supply (oneself) with knowledge of a matter or subject (dictionary.com).
   

3. To convey → information.
   

See also: → informatics, → information theory.

Etymology (EN): Inform, from M.E. informen, from O.Fr. enformer, from L. informare “to shape, form; to form an idea of,” from → in- “into” + → forma “form.”

Etymology (PE): Azdâyidan, from Mid.Pers. azdênidan “to inform,” from azd “information, proclamation; known” (loaned into Arm. azd), from O.Pers. azdā “known,” azdā kar “to become known;” Av. azdā “known;” Sogdian ‘zd’ “informed, known;” cf. Skt. addhā’ “manifestly; certainly, truly,” addhāti “sage.”

A person who gives → information.

See also: From → inform + -ant a suffix forming adjectives and nouns from verbs.

A person who gives → information.

See also: From → inform + -ant a suffix forming adjectives and nouns from verbs.

The science concerned with gathering, manipulating, storing, retrieving, and classifying recorded → information. Also called → information science, computer science.

See also: Informatics, from informat(ion), → information + → ics.

The science concerned with gathering, manipulating, storing, retrieving, and classifying recorded → information. Also called → information science, computer science.

See also: Informatics, from informat(ion), → information + → ics.

1. Knowledge gained through study, communication, research, instruction, etc.
   

2. Knowledge communicated or received concerning a particular fact or circumstance; news.
   

3. The act or fact of informing.
   

4. A sequence of signals that conveys a message to a receiver. Information does not exist on its own. It is contained within something and is coded. The notion of information involves → uncertainty and → randomness; hence the necessity for calling on → probability theory and → statistics.
   

See also:

→ information content, → information entropy, → information flow, → information paradox, → information science, → information technology, → information theory, → infosphere, → quantum information, → entropy.

See also: Verbal noun of → inform.

1. Knowledge gained through study, communication, research, instruction, etc.
   

2. Knowledge communicated or received concerning a particular fact or circumstance; news.
   

3. The act or fact of informing.
   

4. A sequence of signals that conveys a message to a receiver. Information does not exist on its own. It is contained within something and is coded. The notion of information involves → uncertainty and → randomness; hence the necessity for calling on → probability theory and → statistics.
   

See also:

→ information content, → information entropy, → information flow, → information paradox, → information science, → information technology, → information theory, → infosphere, → quantum information, → entropy.

See also: Verbal noun of → inform.

The → negative of the → logarithm of the → probability that a particular
→ message or → symbol will be emitted by a → source.

See also: → information; → content.

The → negative of the → logarithm of the → probability that a particular
→ message or → symbol will be emitted by a → source.

See also: → information; → content.

The measure of information, which is usually expressed by the average number of bits needed for storage or communication. In other words, the degree to which the values of a → random variable X
are dispersed. If the → probability density function of X is P(x), the entropy is defined by: H(X) = -Σ P(x) log P(x). Also called → Shannon entropy.

See also: → information; → entropy.

The measure of information, which is usually expressed by the average number of bits needed for storage or communication. In other words, the degree to which the values of a → random variable X
are dispersed. If the → probability density function of X is P(x), the entropy is defined by: H(X) = -Σ P(x) log P(x). Also called → Shannon entropy.

See also: → information; → entropy.

The flow of data into a system or to the end users.

See also: → information; → flow.

The flow of data into a system or to the end users.

See also: → information; → flow.

A paradox raised in 1976 by S. Hawking (1942-2018) whose analysis of the thermodynamic properties of → black holes led him to the prediction that black holes are not in fact black, but radiate due to quantum effects. This implied that, due to the → Hawking radiation, a black hole would eventually evaporate away, leaving nothing. This deduction presented a problem for → quantum mechanics, which maintains that information can never be lost.

This topic is a matter of intense debate. Many solutions have been proposed, but all of them have serious drawbacks. In order to analyze better these solutions one needs a quantum gravity theory, which does not exist at the moment.

In brief, either the idea of → quantum unitarity must be given up, or a mechanism should be found by which information is not lost after it falls into a black hole.

See also: → information; → paradox.

A paradox raised in 1976 by S. Hawking (1942-2018) whose analysis of the thermodynamic properties of → black holes led him to the prediction that black holes are not in fact black, but radiate due to quantum effects. This implied that, due to the → Hawking radiation, a black hole would eventually evaporate away, leaving nothing. This deduction presented a problem for → quantum mechanics, which maintains that information can never be lost.

This topic is a matter of intense debate. Many solutions have been proposed, but all of them have serious drawbacks. In order to analyze better these solutions one needs a quantum gravity theory, which does not exist at the moment.

In brief, either the idea of → quantum unitarity must be given up, or a mechanism should be found by which information is not lost after it falls into a black hole.

See also: → information; → paradox.

Same as → informatics.

See also: → information; → science.

Same as → informatics.

See also: → information; → science.

The science and activity of receiving, storing, processing, and transmitting information by using → computers.

See also: → information; → technology.

The science and activity of receiving, storing, processing, and transmitting information by using → computers.

See also: → information; → technology.

The mathematical theory that defines, quantifies, and analyzes the concept of → information. It involves → probability theory in → transmission of → messages when the → bits of information are subject to various distortions. Its goal is to enable as much information as possible to be reliably stored on a medium, retrieved, or communicated.

See also:
→ information content, → information entropy, → information flow, → information paradox, → information science, → information theory, → quantum information, → entropy.

See also: → information; → theory.

The mathematical theory that defines, quantifies, and analyzes the concept of → information. It involves → probability theory in → transmission of → messages when the → bits of information are subject to various distortions. Its goal is to enable as much information as possible to be reliably stored on a medium, retrieved, or communicated.

See also:
→ information content, → information entropy, → information flow, → information paradox, → information science, → information theory, → quantum information, → entropy.

See also: → information; → theory.

Giving → information, providing information, imparting → knowledge.

See also: From informat-, from L. informatus, from → inform + → -ive.

Giving → information, providing information, imparting → knowledge.

See also: From informat-, from L. informatus, from → inform + → -ive.

A person who provides → information.

See also: From → inform + -er, → -or.

A person who provides → information.

See also: From → inform + -er, → -or.

The global network of all the world’s communications, databases, and sources of information.

See also: → information; → sphere.

The global network of all the world’s communications, databases, and sources of information.

See also: → information; → sphere.

A prefix meaning “below,” used with second elements of any origin.
→ infrared; → infrasound.

Etymology (EN): From L. infra “below, underneath, beneath,” from PIE *ndher; cf. Mod.Pers. zir “below, down,” akin to → under-.

Etymology (PE): Foru-, from foru “down, downward; below; under, beneath; low,” from Mid.Pers. frôt “down, downward;” O.Pers. fravata “forward, downward;” cf. Skt. pravát- “a sloping path, the slope of a mountain.”

A prefix meaning “below,” used with second elements of any origin.
→ infrared; → infrasound.

Etymology (EN): From L. infra “below, underneath, beneath,” from PIE *ndher; cf. Mod.Pers. zir “below, down,” akin to → under-.

Etymology (PE): Foru-, from foru “down, downward; below; under, beneath; low,” from Mid.Pers. frôt “down, downward;” O.Pers. fravata “forward, downward;” cf. Skt. pravát- “a sloping path, the slope of a mountain.”

The invisible part of electromagnetic spectrum possessing wavelengths between those of visible light and those of radio waves, i.e. approximately between about 0.75 and 1000 μm.

Etymology (EN): From L. infra (adv., prep.) “below, underneath, beneath,” inferus “lower,” from PIE *ndher; cf. Av. aδara- (adj.), aδairi- (prep.) “below;” Mid.Pers. êr “below, down; low, under,” adar “low,” azêr “below, under” (Mod.Pers. zir “below, down”); Skt. ádhara- “lower;” O.E. under “under, among”); → red.

Etymology (PE): Forusorx, from foru “down, downward; below; beneath;” Mid.Pers. frôt “down, downward;” O.Pers. fravata “forward, downward;” cf. Skt. pravát- “a sloping path, the slope of a mountain,” + sorx→ red.

The invisible part of electromagnetic spectrum possessing wavelengths between those of visible light and those of radio waves, i.e. approximately between about 0.75 and 1000 μm.

Etymology (EN): From L. infra (adv., prep.) “below, underneath, beneath,” inferus “lower,” from PIE *ndher; cf. Av. aδara- (adj.), aδairi- (prep.) “below;” Mid.Pers. êr “below, down; low, under,” adar “low,” azêr “below, under” (Mod.Pers. zir “below, down”); Skt. ádhara- “lower;” O.E. under “under, among”); → red.

Etymology (PE): Forusorx, from foru “down, downward; below; beneath;” Mid.Pers. frôt “down, downward;” O.Pers. fravata “forward, downward;” cf. Skt. pravát- “a sloping path, the slope of a mountain,” + sorx→ red.

A two-dimensional infrared imaging device, consisting of an array of small, individual electronic detectors, each of which records a pixel in the image.

See also: → infrared; → array.

A two-dimensional infrared imaging device, consisting of an array of small, individual electronic detectors, each of which records a pixel in the image.

See also: → infrared; → array.

An orbiting infrared telescope (60 cm mirror) which successfully operated from launch
in January 1983 until the supply of coolant ran out in November 1983. It was a collaborative mission between NASA, the Netherlands, and the UK, and mapped 95% of the whole sky in the wavelength bands 12, 25, 60, and 100 microns.

See also: → infrared; → astronomical; → satellite.

An orbiting infrared telescope (60 cm mirror) which successfully operated from launch
in January 1983 until the supply of coolant ran out in November 1983. It was a collaborative mission between NASA, the Netherlands, and the UK, and mapped 95% of the whole sky in the wavelength bands 12, 25, 60, and 100 microns.

See also: → infrared; → astronomical; → satellite.

The study of infrared properties of astronomical objects.

See also: → infrared; → astronomy.

The study of infrared properties of astronomical objects.

See also: → infrared; → astronomy.

An optical camera equipped with a → detector which is sensitive to → infrared radiation.

See also: → infrared; → camera.

An optical camera equipped with a → detector which is sensitive to → infrared radiation.

See also: → infrared; → camera.

Wispy, extended structures seen above and below the plane of the Galaxy in the infrared maps of the sky (60-100 microns) produced by the → Infrared Astronomical Satellite (IRAS).

See also: → infrared; L. cirrus “curl, tuft, plant filament like a tuft of hair.”

Wispy, extended structures seen above and below the plane of the Galaxy in the infrared maps of the sky (60-100 microns) produced by the → Infrared Astronomical Satellite (IRAS).

See also: → infrared; L. cirrus “curl, tuft, plant filament like a tuft of hair.”

A → dark cloud characterized by a → visual extinction A_v≥ 10² mag. IRDCs are opaque even at 8 μm, and can be seen in silhouette against the bright diffuse → mid-infrared emission in the → interstellar medium.

See also: → infrared; → dark; → cloud.

A → dark cloud characterized by a → visual extinction A_v≥ 10² mag. IRDCs are opaque even at 8 μm, and can be seen in silhouette against the bright diffuse → mid-infrared emission in the → interstellar medium.

See also: → infrared; → dark; → cloud.

A thermal device for observing and measuring → infrared radiation.

See also: → infrared; → detector.

A thermal device for observing and measuring → infrared radiation.

See also: → infrared; → detector.

The portion of → electromagnetic radiation from → astrophysical objects in → infrared frequencies.

See also: → infrared; → emission.

The portion of → electromagnetic radiation from → astrophysical objects in → infrared frequencies.

See also: → infrared; → emission.

Infrared → emission from a star in excess of that expected from a → blackbody with the temperature corresponding to the temperature of the star.

See also: → infrared; → excess.

Infrared → emission from a star in excess of that expected from a → blackbody with the temperature corresponding to the temperature of the star.

See also: → infrared; → excess.

A galaxy that emits most of its energy in the infrared region of the spectrum. Such galaxies are thought to have unusually high rates of star formation and are also described as → starburst galaxies.

See also: → infrared; → galaxy.

A galaxy that emits most of its energy in the infrared region of the spectrum. Such galaxies are thought to have unusually high rates of star formation and are also described as → starburst galaxies.

See also: → infrared; → galaxy.

Imaging with an infrared detector.

See also: → infrared; → imaging.