An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 397
  ویسپ‌دانا، ویسپ‌آگاه   
visp-dânâ (#), visp-âgâh (#)

Fr.: omniscient   

Having infinite knowledge, awareness, understanding, or insight.

omni-; L. scient "knowing," → science.

Visp-, → omni-, dânâ "knowing, learned," → science; âgâh "aware," → look.

bar- (#), dar- (#)

Fr.: sur   

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

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").

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-.


Fr.: en ligne   

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.

on; → line.

on-line reduction
  باز‌هازشِ بر-خط   
bâzhâzeš-e bar-xatt

Fr.: réduction enligne   

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

on-line; → reduction.

on-source observation
  نپاهشِ بر-خن   
nepâheš-e bar-xan

Fr.: observation sur la source   

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

on-; → dource; → observation.

on-the-spot (OTS) approximation
  نزدینش ِ درجا   
nazdineš-e darjâ


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.

on; → spot; → approximation.

Nazdineš, → approximation; dar "in," from Mid.Pers. andar, → intra-.

yek (#)

Fr.: un   

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.

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.

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.

one-dimensional flow
  تچان ِ یک-وامونی   
tacân-e yek-vâmuni

Fr.: écoulement uni-dimensionnel   

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).

one; → dimensional; → flow.

one-to-one correspondence
  هم‌پتوازیِ یک-به-یک   
hampatvâzi-ye yek-be-yek

Fr.: correspondance un à un   

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.

one; → correspondence.

piyâz (#)

Fr.: oignon   

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

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.

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."

  ایواز، تنها   
ivâz, tanhâ (#)

Fr.: seulement   

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

M.E., from O.E. anlic, from ân, → one.

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.

hasti-šenâsi (#)

Fr.: ontologie   

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.

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.

Hasti-šenâsi, from hasti "existence," from hastan "to be," → entity, + -šenâsi, → -logy.

Oort cloud
  ابرِ اورت   
abr-e Ort (#)

Fr.: nuage de Oort   

A huge theoretical cloud of → comets surrounding the Sun between about 50,000 and 100,000 → astronomical units and thought to be the reservoir of → long-period comets entering the inner solar system.

Named after Jan Hendrik Oort (1900-1992), a Dutch astronomer who proposed its existence in 1950. He also made major contributions to our knowledge of the structure and rotation of the Milky Way Galaxy; → cloud.

Oort limit
  حدِ اورت   
hadd-e Oort

Fr.: limite de Oort   

1) The upper limit for the density of all matter in the plane of the Galaxy near the Sun's locality, as calculated from the velocities and distribution of stars in relation to the gravitational field of the Galactic disk. The value is 0.14 solar masses per cubic parsec, or 9.5 x 10-24 g cm3.
2) The outer boundary of the → Oort cloud. The current estimate is about 100,000 → astronomical units from the Sun, which is approximately one third of the distance to the nearest star → Alpha Centauri.

Oort cloud; → limit.

Oort minimum
  کمینه‌ی ِ اورت   
kamine-ye Oort

Fr.: minimum de Oort   

A 40-year period of unusually low → solar activity, from about 1010 to 1050. See also the → Maunder minimum.

Oort cloud; → minimum.

Oort's constants
  پایاهایِ اورت   
pâyâhâ-ye Oort

Fr.: constantes de Oort   

Two parameters, denoted A and B, that describe the major features of our Galaxy's differential rotation in the Sun's neighbourhood. A is one-half of the shear and equal to +14.4 ± 1.2 km s-1 kpc-1, and B, one-half of the vorticity, equal to -12.0 ± 2.8 km s-1 pc-1.

Oort cloud; → constant.

kederi (#)

Fr.: opacité   

1) General: The state or quality of being opaque.
2) A measure of the absorption of photons on their way from the stellar center to the surface. Opacity depends upon the frequency of the radiation, the density, the chemical composition, and the thermodynamic state of the gas. For a given density, the hotter the gas the lower the opacity, since the gas absorbs less readily, as described by → Kramers' law. Conversely, the cooler the gas the higher the opacity. See also → stellar pulsation, → kappa mechanism, → valve mechanism, → partial ionization zone.

From Fr. opacité, from L. opacitatem (nom. opacitas) "shade, shadiness," from opacus "shaded, dark, opaque."

Kederi, from keder "opaque," from Ar. kader + -i suffix forming nouns from adjectives.

opâl (#)

Fr.: opale   

A → mineral, an amorphous form of → silica, SiO2 with some → water of → hydration, found in many varieties and colors, including a form that is milky white.

M.E., from M.Fr. opalle, from L. opalus, from Gk. opallios "opal, gem;" probably from a source akin to Skt. upala "jewel, precious stone."

Loan from E., as above.


Fr.: opalescence   

1) The state of being → opalescent, or emitting an → iridescence like that of an opal.
2) Physics: The milky → iridescent appearance of a dense transparent medium when it is illuminated by → polychromatic visible radiation (such as sunlight) due to local → fluctuations in its density and therefore in its → refractive index. → critical opalescence.

opal; → -escence.


Fr.: opalescent   

Exhibiting a play of colors like that of the opal.

opal; → -escent.

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