An Etymological Dictionary of Astronomy and Astrophysics

Adverb, used as prefix denoting “in, into, onto; toward; with continuous activity,” etc.

Etymology (EN): O.E. on, variant of an “in, on, into,” from P.Gmc. (cf. Du. aan, Ger. an, Goth. ana “on, upon”), from PIE base *ano “on” (cf. Av. ana “on,” Gk. ana “on, upon,” L. an-, O.C.S. na, Lith. nuo “down from”).

Etymology (PE): Bar “on; up; upon; in; into; at; forth; with; near; before; according to” (Mid.Pers. abar; O.Pers. upariy “above; over, upon, according to;” Av. upairi “above, over,” upairi.zəma- “located above the earth;” cf. Gk. hyper- “over, above;” L. super-; O.H.G. ubir “over;” PIE base *uper “over”).
Dar- “in,” from Mid.Pers. andar, → intra-.

Adverb, used as prefix denoting “in, into, onto; toward; with continuous activity,” etc.

Etymology (EN): O.E. on, variant of an “in, on, into,” from P.Gmc. (cf. Du. aan, Ger. an, Goth. ana “on, upon”), from PIE base *ano “on” (cf. Av. ana “on,” Gk. ana “on, upon,” L. an-, O.C.S. na, Lith. nuo “down from”).

Etymology (PE): Bar “on; up; upon; in; into; at; forth; with; near; before; according to” (Mid.Pers. abar; O.Pers. upariy “above; over, upon, according to;” Av. upairi “above, over,” upairi.zəma- “located above the earth;” cf. Gk. hyper- “over, above;” L. super-; O.H.G. ubir “over;” PIE base *uper “over”).
Dar- “in,” from Mid.Pers. andar, → intra-.

The state when two or more devices are directly connected and are communicating efficiently.
Of computers, operating under the direct control of, or connected to, a main computer.

See also: → on; → line.

The state when two or more devices are directly connected and are communicating efficiently.
Of computers, operating under the direct control of, or connected to, a main computer.

See also: → on; → line.

Preliminary reduction of observational data at a telescope simultaneously with their acquisition.

See also: → on-line; → reduction.

Preliminary reduction of observational data at a telescope simultaneously with their acquisition.

See also: → on-line; → reduction.

In comparison with → off-source observation,
an observation which is concerned with the source itself.

See also: → on-; → dource;
→ observation.

In comparison with → off-source observation,
an observation which is concerned with the source itself.

See also: → on-; → dource;
→ observation.

An approximation in the treatment of photoionized → H II regions, whereby secondary ionizing photons are absorbed immediately very close to their site of emission. The secondary photons, produced by → radiative recombinations directly to the → ground states, are thus ignored with respect to the ionizing photons emitted by the → exciting star. The OTS approximation requires that the ionized gas be sufficiently dense so that secondary ionizing photons are very likely absorbed within the H II region.

Etymology (EN): → on; → spot; → approximation.

Etymology (PE): Nazdineš, → approximation; dar “in,” from Mid.Pers. andar, → intra-.

An approximation in the treatment of photoionized → H II regions, whereby secondary ionizing photons are absorbed immediately very close to their site of emission. The secondary photons, produced by → radiative recombinations directly to the → ground states, are thus ignored with respect to the ionizing photons emitted by the → exciting star. The OTS approximation requires that the ionized gas be sufficiently dense so that secondary ionizing photons are very likely absorbed within the H II region.

Etymology (EN): → on; → spot; → approximation.

Etymology (PE): Nazdineš, → approximation; dar “in,” from Mid.Pers. andar, → intra-.

1. The smallest whole number, symbol 1; unity. The → multiplicative identity for real and complex numbers.
   

2. Being or amounting to a single unit or individual or entire thing, item, or object rather than two or more; a single.

Etymology (EN): O.E. an, from P.Gmc. *ainaz (cf. O.N. einn, Dan. een, O.Fris. an, Du. een, Ger. ein, Goth. ains), PIE base *oinos, cognate with Pers. yek, as below.

Etymology (PE): Yek “one, alone,” from Mid.Pers. êwak, êv, yak, êk; cf. Baluci hivak “one, single” (Proto-Iranian *aiua-ka-); O.Pers. aiva- “one, alone;” Av. aēuua- “one, alone;” Skt. éka- “one, alone, single;” Gk. oios “alone, lonely;” L. unus “one;” E. one.

1. The smallest whole number, symbol 1; unity. The → multiplicative identity for real and complex numbers.
   

2. Being or amounting to a single unit or individual or entire thing, item, or object rather than two or more; a single.

Etymology (EN): O.E. an, from P.Gmc. *ainaz (cf. O.N. einn, Dan. een, O.Fris. an, Du. een, Ger. ein, Goth. ains), PIE base *oinos, cognate with Pers. yek, as below.

Etymology (PE): Yek “one, alone,” from Mid.Pers. êwak, êv, yak, êk; cf. Baluci hivak “one, single” (Proto-Iranian *aiua-ka-); O.Pers. aiva- “one, alone;” Av. aēuua- “one, alone;” Skt. éka- “one, alone, single;” Gk. oios “alone, lonely;” L. unus “one;” E. one.

A hypothetical flow in which all the flow parameters may be expressed as functions of time and one space coordinate only. This single space coordinate is usually the distance measured along the center-line of some conduit in which the fluid is flowing (B. Massey, Mechanics of Fluids, Taylor & Francis, 2006).

See also: → one; → dimensional; → flow.

A hypothetical flow in which all the flow parameters may be expressed as functions of time and one space coordinate only. This single space coordinate is usually the distance measured along the center-line of some conduit in which the fluid is flowing (B. Massey, Mechanics of Fluids, Taylor & Francis, 2006).

See also: → one; → dimensional; → flow.

A → magnetohydrodynamics treatment in which the → plasma consists only of one particle species and moves with the bulk speed. The thermal motion of the particles is neglected and thus there is no motion of particles relative to each other.

See also: → one; → fluid; → magnetohydrodynamics.

A → magnetohydrodynamics treatment in which the → plasma consists only of one particle species and moves with the bulk speed. The thermal motion of the particles is neglected and thus there is no motion of particles relative to each other.

See also: → one; → fluid; → magnetohydrodynamics.

A relationship between two distinct sets of elements such that every member of the first set can be paired with a unique element in the second set; and every member of the second set can be paired with a unique element in the first set. Two sets so related are said to be isomorphic.

See also: → one; → correspondence.

A relationship between two distinct sets of elements such that every member of the first set can be paired with a unique element in the second set; and every member of the second set can be paired with a unique element in the first set. Two sets so related are said to be isomorphic.

See also: → one; → correspondence.

A plant, Allium cepa, of the amaryllis family, having an edible, succulent, pungent bulb (Dictionary.com).

Etymology (EN): M.E., from Anglo-French union, O.Fr. oignon “onion,” from L. unio-, also “pearl,” literally “one, unity;” sense connection is the successive layers of an onion.

Etymology (PE): Mid.Pers. payâz, payâc; cf. Sogd. piyâk “onion,” Yidgha piq, Vakhi piûk, Yazghulami piyeq, Kurd. pivaz; maybe related to PIE *peuk- “to prick, to sting, to stab,” because of its pungent taste;
cf. Gk. peukos “sting, prick, cusp, peak.”

A plant, Allium cepa, of the amaryllis family, having an edible, succulent, pungent bulb (Dictionary.com).

Etymology (EN): M.E., from Anglo-French union, O.Fr. oignon “onion,” from L. unio-, also “pearl,” literally “one, unity;” sense connection is the successive layers of an onion.

Etymology (PE): Mid.Pers. payâz, payâc; cf. Sogd. piyâk “onion,” Yidgha piq, Vakhi piûk, Yazghulami piyeq, Kurd. pivaz; maybe related to PIE *peuk- “to prick, to sting, to stab,” because of its pungent taste;
cf. Gk. peukos “sting, prick, cusp, peak.”

An adverb meaning without others or anything further; alone; solely; exclusively. → if and only if.

Etymology (EN): M.E., from O.E. anlic, from ân, → one.

Etymology (PE): Ivâz, from Mid.Pers. êvâz/êvâc, from Proto-Iranian *aiua-ka-; cf. Pers. yek, → one.
Tanhâ “only,” from Mid.Pers. tanihâ “alone,” literally “by one person,” from tan “body, person;” Av. tanu- “body, person;” cf. Skt. tanu- “body, person;” perhaps related to Proto-Iranian *tan-, PIE root *ten- “to extend, stretch,” → tension.

An adverb meaning without others or anything further; alone; solely; exclusively. → if and only if.

Etymology (EN): M.E., from O.E. anlic, from ân, → one.

Etymology (PE): Ivâz, from Mid.Pers. êvâz/êvâc, from Proto-Iranian *aiua-ka-; cf. Pers. yek, → one.
Tanhâ “only,” from Mid.Pers. tanihâ “alone,” literally “by one person,” from tan “body, person;” Av. tanu- “body, person;” cf. Skt. tanu- “body, person;” perhaps related to Proto-Iranian *tan-, PIE root *ten- “to extend, stretch,” → tension.

1. Classical philosophy: That part of metaphysics which is concerned with the nature of existence or the essence of things.
   

2. Contemporary philosophy: The conceptions of existence in general, such as those dealt with in various versions of existentialism.
   

3. Informatics: A description of knowledge as a set of concepts within a domain and the relationships that can exist between those concepts. An ontology is designed for the purpose of enabling knowledge sharing and reuse.

Etymology (EN): From Mod.L. ontologia, from Gk. on (genitive ontos) “being” (pr.p. of einai “to be”), akin to L. esse “to be;” Pers. hastan, astan “to be,” hasti “existence, being,” as below; + -logia, → -logy.

Etymology (PE): Hasti-šenâsi, from hasti “existence,” from hastan “to be,” → entity, + -šenâsi, → -logy.

1. Classical philosophy: That part of metaphysics which is concerned with the nature of existence or the essence of things.
   

2. Contemporary philosophy: The conceptions of existence in general, such as those dealt with in various versions of existentialism.
   

3. Informatics: A description of knowledge as a set of concepts within a domain and the relationships that can exist between those concepts. An ontology is designed for the purpose of enabling knowledge sharing and reuse.

Etymology (EN): From Mod.L. ontologia, from Gk. on (genitive ontos) “being” (pr.p. of einai “to be”), akin to L. esse “to be;” Pers. hastan, astan “to be,” hasti “existence, being,” as below; + -logia, → -logy.

Etymology (PE): Hasti-šenâsi, from hasti “existence,” from hastan “to be,” → entity, + -šenâsi, → -logy.