An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13003 Search : far
on-line
  بر-خط   
bar-xatt

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

Fr.:   

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-.

one
  یک   
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-fluid magnetohydrodynamics
  مغنات-و-هیدروتوانیک ِ تک-شاره   
meqnâtohidrotavânik-e tak-šâre

Fr.: magnétohydrodynamique à une fluide   

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.

one; → fluid; → magnetohydrodynamics.

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.

onion
  پیاز   
piyâz (#)

Fr.: oignon   

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

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."

only
  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.

ontology
  هستی‌شناسی   
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.

opacity
  کدری   
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.

opal
  اپال   
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.

opalescence
  اپالستی   
opâlesti

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.

opalescent
  اپالست   
opâlest

Fr.: opalescent   

Exhibiting a play of colors like that of the opal.

opal; → -escent.

opaque
  کدر   
keder (#)

Fr.: opaque   

General: Not permitting a radiation to pass through.
Meteo.: A condition where a material, such as a cloud, blocks the passage of radiant energy, especially light.

Adj. form of → opacity.

<< < -es -iv -ti 21- a p abe abs abs acc acc acc act act ada adi ads aes Age Alb Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app app arb are ari art ass ast ast ast Atl ato ato Aug aut awa azi bac bal Bar Bar Bay bea Bep Bet BIC bij bin bio bir bla bla blu blu bol Boo bou Bq bre bri bub B[e cal cal can car car Cas cat cau cel cen Cer cha cha cha che chi CI cir cir cla cle clo clu co- cob coh col col col com com com com com com com com Com con con con con con con con con con con con con coo cor cor cor cos cos cos cou cov cra cri cro cry cum cur cyc d'A dar dat DC dea dec dec dec def def deh Del den dep des det deu dia dif dif dif dim dip Dir dis dis dis dis dis div dom dos dou dri Dum dus dyn dyn ear eas ecl Edd eff Ein eje ele ele ele ele eli emb emi Enc ene ens eph epo equ equ eru eth Eul eve evo exc exc exi exo exp exp ext ext Fab fai Fan fea fem fer fie fil fir fir fla flo flu foc For for fos fra fre fre fro fun g m Gal gal gal gas gau gel gen geo geo geo gho gla gno gra gra gra gra Gre Gre gro gyr had hal har Har HD hea hel hel Her Her Hic hig hip hol hor hos hov Hub hun hyd hyd Hyd hyp IC ide ill ima imp imp inc inc ind ind inf inf inf inf inj ins ins int int int int int int int int inv Io ion iro isl iso iso Jal JHK Jul jur Kel Kep kin kne L2 Lag lam Lap lar lat law Lec len Lep lib lig lin lin lin liq lit loc log lon los low lum lun lux Lyr mac mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mom moo mor mov mul mur Na nar nat nea neg Nes neu New New Nic nod non non non Nor nov nuc nul num OB obl obs occ Ock off Ohm on- ope opi opt opt orb orb ord Ori ort OSI out ove ozo pal pan par par par par pat pec pen per per per per per Pfu pha pho pho pho phy pie pix Pla pla pla pla Pli Poi pol pol pol pol por pos pos pow pre pre pre pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua qui rad rad rad rad rad rad rak ran rat Ray rea rec rec rec red ref ref reg reg rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set sha SHB sho sib sid sil sim sin sit sky slo Sne Soc sol sol sol sol son sou spa spa spe spe spe spe sph spi spo Squ sta sta sta sta ste ste ste sto str str str sub sub sub sum sup sup sup sup sur sus sym syn T d tap tec tem ten tes the the the the thi thr tid tim tip ton tor tow tra tra tra tra tri tri tru tub tur two Typ ult un- und uni uni uno upp urg UX Van var veg vel ver vib vio vir vis Voi vow wan wat wav WC wea wel whi Wil wir WNh wor X-r yel Z C zer ZZ > >>