An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 394

Fr.: être d'avis que   

To hold or express an opinion.

Verb for → opinion.


Fr.: opinion   

1) A belief or judgment that rests on grounds insufficient to produce complete certainty ( See also: → public opinion.
2) A personal view, attitude, or appraisal (
3) Law: The formal statement by a judge or court of the reasoning and the principles of law used in reaching a decision of a case (

M.E., from O.Fr., from L. opinion- "opinion, conjecture; appreciation," from opinari "to think, judge, suppose," from PIE *op- "to choose."

Pažân, from Pashtu pežân, Sogd. patzân, Khotanese paysân- "to know;" Av. paiti-zan- "to recognize, acknowledge, appreciate;" from prefix paiti- + zan- "to know, have knowledge;" cf Mod.Pers. farzâné "intelligent; wise," dân-, dânestan "to know," variant šenâxtan "to know, recognize," → science.

Oppenheimer-Volkoff limit
  حدِ ا ُپنهایمر-وُلکوف   
hadd-e Oppenheimer-Volkoff

Fr.: limite d'Oppenheimer-Volkoff   

The upper bound to the mass of a → neutron star, the mass beyond which the pressure of neutron → degenerate matter is not capable of preventing the → gravitational collapse which will lead to the formation of a → black hole. Modern estimates range from approximately 1.5 to 3.0 → solar masses. The uncertainty in the value reflects the fact that the → equation of state for → overdense matter is not well-known.

Oppenheimer, J.R., Volkoff, G.M., 1939, Physical Review 55, 374. Named after Robert Oppenheimer (1904-1967), an American theoretical physicist, and George Volkoff (1914-2000), a Canadian physicist, who first calculated this limit. Oppenheimer is widely known for his role as the scientific director of the Manhattan Project, the World War II effort to develop the first nuclear weapons at the secret Los Alamos laboratory in New Mexico; → limit.


Fr.: opposant, adversaire   

A person who is on an opposing side in a game, contest, controversy, or the like; adversary (

L. opponent-, p.p. of opponere "to oppose, to object to," literally "set against, set opposite," from op- variant of ob- before p "against" + ponere "to put, set, place," → position.

Pâdistgar, from pâdist, → opposition, + -gar, → -or.


Fr.: opportun   

1) Appropriate, favorable, or suitable.
2) Occurring or coming at an appropriate time; well-timed (

M.E., from O.Fr. opportun and directly from L. opportunus "fit, convenient, suitable," from the phrase ob portum veniens "coming toward a port," literally "a wind blowing to harbor," from ob "to, toward" + portus "access, harbor."

Nikvâ "appropriate, suitable," from nik, nêk, neku "good, beautiful, elegant;" Mid.Pers. nêk, nêvak, nêkôg "good, beautiful;" O.Pers. naiba- + -vâ relation suffix (as in pišvâ, pilévâ); alternatively, nikvâ "good/appropriate wind," from nik + "wind," variant of bâd, → wind, in several dialects.


Fr.: opportunisme   

The policy or practice, as in politics, business, or one's personal affairs, of adapting actions, decisions, etc., to expediency or effectiveness regardless of the sacrifice of ethical principles (

opportune + → -ism.


Fr.: opportuniste   

A person who adapts his actions, responses, etc, to take advantage of opportunities, circumstances, etc. (

opportune + → -ist.


Fr.: opportunité   

1) An appropriate or favorable time or → occasion.
2) A situation or condition favorable for attainment of a goal (

opportune + → -ity.


Fr.: s'opposer à, faire opposition à; opposer   

1) To act against or provide resistance to.
2) To stand in the way of; hinder; obstruct (

M.E., from O.Fr. oposer "to oppose, resist; contradict," from poser "to place, lay down," blended with L. opponere "to oppose, to object," → position.

Pâdistidan, infinitive from pâdist, → opposition.

  ۱) رو-به-رو؛ ۲) پادیستین؛ ۳) پادچم   
1) ru-be-ru; 2) pâdistin; 3) pâdcem

Fr.: 1) opposé, d'en face; 2) contraire, opposé; 3) antonyme   

1) Situated, placed, or lying face to face with something else or each other, or in corresponding positions with relation to an intervening line, space, or thing: opposite ends of a room (
2) Contrary or radically different in some respect common to both, as in nature, qualities, direction, result, or significance; opposed (
3) An → antonym.

M.E., from M.Fr., from L. oppositus, p.p. of opponere, → opposition.

1) Ru-be-ru "face to face," → surface.
2) Pâdistin, from pâdist, → opposition, + -in, as in zirin, zebarin, pišin, pasin.
3) Pâdcem, → antonym.

  ۱، ۲) پادیست؛ ۳، ۴) پادیستان   
1, 2) pâdist; 3, 4) pâdistân

Fr.: opposition   

1) The action of opposing, resisting, or combating.
2) A person or group of people opposing, criticizing, or protesting something, someone, or another group (
3) The position of a solar system body having its orbit outside that of the Earth when the Earth is in a line between the Sun and the body. At opposition the body has a solar → elongation of 180°, and is closest to the Earth. It will, in principle, be visible throughout the night. It will rise in the east as the Sun sets in the west and it will set as the Sun rises. This is because, at opposition, the body and the Sun are 12 hours apart. The inner planets can never be in opposition. The opposite of opposition is → conjunction.
4) Two periodic quantities of the same frequency are said to be in opposition when the → phase difference between them is one half of a → period.

Verbal noun of → oppose.

Pâdist "standing against," from pâd- "agaist, contrary to," → anti-, + ist present stem of istâdan "to stand" (Mid.Pers. êstâtan, O.Pers./Av. sta- "to stand; to set;" Av. hištaiti; cf. Skt. sthâ- "to stand;" Gk. histemi "put, place, weigh," stasis "a standing still;" L. stare "to stand;" Lith. statau "place;" Goth. standan; PIE base *sta- "to set, stand").
Pâdistân, from pâdist + -ân suffix of place and time.


Fr.: opter   

To make a choice; choose (usually followed by for).

From Fr. opter "to choose," from L. optare "to choose, desire, wish for," from L. optare "to desire, choose," from PIE root *op- "to choose, prefer."

Optidan, from L. optare, as above.

  اپتانه، اپتمند   

Fr.: optatif   

Of, relating to, or constituting a verbal mood that is expressive of wish or desire.

From M.Fr. optatif, from L. optativus, from optatus, p.p. of optare, → opt, + -ivus, → -ive.

Optâné, optmand, from opt present stem of optidan, → opt, + adj. suffixes -âné, -mand. -yi.

  ۱) نوری، نوریک؛ ۲) دیدگانی   
1) nuri, nurik; 2) didgâni

Fr.: optique   

1) Of or pertaining to the eye or sight.
2) Same as → optical.

From M.Fr. optique, from M.L. opticus "of sight or seeing," from Gk. optikos "of or having to do with sight," from optos "seen, visible," from op-, root of opsesthai "be going to see," related to ops "eye," from PIE *okw- "eye/see."

1) Nuri, nurik, from nur, → light + -i, -ik adj. suffix → -ic.
2) Didgâni, related to didgân "eyes," plural of didé "eye; seen," from didan "to see" (Mid.Pers. ditan "to see, regard, catch sight of, contemplate, experience;" O.Pers. dī- "to see;" Av. dā(y)- "to see," didāti "sees;" cf. Skt. dhī- "to perceive, think, ponder; thought, reflection, meditation," dādhye; Gk. dedorka "have seen").

optic axis
  آسه‌یِ نوری   
âse-ye nuri

Fr.: axe optique   

The direction in a doubly refracting crystal in which light is propagated without double refraction.

optic; → axis.

  ۱) نوری، نوریک؛ ۲) دیدگانی   
1) nuri, nurik; 2) didgâni

Fr.: optique   

1) Of, pertaining to, or applying optics or the principles of optics.
2) Of or pertaining to sight or vision; visual; of or pertaining to the eye.

From → optic + → -al.


optical aberration
  بیراهشِ نوری   
birâheš-e nuri

Fr.: aberration optique   

An imperfection in the imaging properties of a lens or mirror. The main aberrations are → chromatic aberration, → spherical aberration, → coma, → astigmatism, → field curvature, → distortion.

optical; → aberration.

optical activity
  ژیرندگیِ نوری   
žirandegi-ye nuri

Fr.: activité optique   

The property possessed by some substances and their solutions of rotating the plane of vibration of → polarized light. When a beam of → linearly polarized light is sent through an optically active substance, such as crystalline quartz and sugar solution, the direction of vibration of the emerging linearly polarized light is found to be different from the original direction. Those which rotate the → plane of polarization to the right, for an observer looking in the incoming beam, are called → dextrorotatory or right handed; those which rotate it to the left, → levorotatory or left handed. Optical activity may be due to an asymmetry of molecules of a substance (solutions of cane sugar) or it may be a property of a crystal as a whole (crystalline quartz).

optical; → activity.

optical analysis
  آنالسِ نوری   
ânâlas-e nuri

Fr.: analyse optique   

The mathematical evaluation of an optical system to determine its basic optical properties and image quality characteristics.

optical; → analysis.

optical autocorrelator
  خودهم‌باز‌آنگرِ نوری   
xod-hambâzângar-e nuri

Fr.: autocorrélateur optique   

An instrument used to test lenses by utilizing the → optical transfer function. It consists of a HeNe laser, a beamsplitter and two mirrors.

optical; → autocorrelator.

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