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: 726
reflecting circle
  دایره‌ی ِ بازتابی   
dâyere-ye bâztâbi

Fr.: cercle à réflexion   

An instrument for measuring angular distances, based on the same principle as the → octant, but with a full circular limb divided into 720°. It was invented in 1752 by the German astronomer Johann Tobias Mayer (1723-1762) to improve on the octant which often gave wrong results because of incorrect graduations. The instrument consisted of an index arm and a small telescope, both pivoted centrally. In practice, the index arm is first set to zero, and the telescope rotated until the two images of a star are seen in coincidence (the one directly, the other by double reflection). Then the index arm is freed, and rotated until the other object is seen in coincidence after double reflection. The angle has now been measured, but the double operation is repeated several times, and the final angle divided by the number of repetitions to find a mean value. Hence, the instrument was sometimes called a "repeating circle." The reflecting circle had little success because it was heavy and uncomfortable to use. Its improved form is called → Borda circle.

reflection; → circle.

reflecting telescope
  تلسکوپ ِ بازتابی، دوربین ِ ~   
teleskop-e bâztâbi (#), durbin-e ~ (#)

Fr.: télescope réflecteur   

A telescope in which the image is produced by reflection of light by a concave mirror.

Reflecting, verbal adj. of → reflect; → telescope.

reflection
  بازتاب   
bâztâb (#)

Fr.: réflexion   

The return of radiation after striking a surface, without change in wavelength. If the surface is smooth, reflection is regular, otherwise it is diffuse. → diffuse reflection; → specular reflection.

Verbal noun of → reflect.

reflection coefficient
  همگر ِ بازتاب   
hamgar-e bâztâb (#)

Fr.: coefficient de réflexion   

The ratio given by the → amplitude (or energy) of a reflected wave divided by the amplitude (or energy) of the incident wave.

reflection; → coefficient.

reflection factor
  کروند ِ بازتاب   
karvand-e bâztâb

Fr.: facteur de réflexion   

The ratio of total flux that is reflected from a surface to the incident flux. Also called reflectance, reflectivity.

reflection; → factor.

reflection nebula
  میغ ِ بازتابی   
miq-e bâztâbi

Fr.: nébuleuse par réflexion   

A type of nebula that is visible from its reflection of starlight. Bright stars near reflection nebulae emit light into the region that is reflected by the large amount of dust there. The size of the dust grains causes blue light to be reflected more efficiently than red light, so these reflection nebulae frequently appear blue in color.

reflection; → nebula.

reflective
  بازتابی   
bâztâbi (#)

Fr.: réfléchissant, réflecteur   

That reflects; reflecting. Of or pertaining to reflection.

From → reflect + -ive a suffix of adjectives and nouns of adjectival origin.

Bâztâbi adj. of bâztâb, → reflection.

reflectivity
  بازتابندگی   
bâztâbandegi

Fr.: réflectivité   

Same as → reflectance; → reflection factor.

From → reflective + → -ity.

reflector
  بازتابگر   
bâztâbgar (#)

Fr.: réflecteur   

1) A → reflecting telescope.
2) A type of conducting surface or material used to → reflect radiant energy.

From reflect, → reflection, + → -or.

reform
  ۱) بازدیسی؛ ۲) بازدیسیدن   
1) bâzdisi; 2) bâzdisida,

Fr.: 1) réforme; réformer   

1) (n.) The improvement, amendment, or reorganization of something that is considered to be wrong, ineffective, or unsatisfactory; e.g. calendar reform.
2) (v.tr.) To change and improve by correction of faults, alteration, substitution, abolition, etc.

From M.E. reformen, from M.Fr. reformer, from O.Fr., from L. reformare "to form again, change, alter," from → re- "again" + formare "to form," from forma "form, mold, shape, case," origin unknown.

1) Bâzdisi, from bâz- "again," → re-, + dis, disé "form, appearance," (variants -diz, -diš (tandis "body form, like a body; effigy; statute;" mâhdis "moon-like;" šabdiz "night color; a horse of dark rusty color;" andiš- "to think, contemplate"); Mid.Pers. dêsag "form, appearance," dêsidan "to form, build;" Av. daēs- "to show," daēsa- "sign, omen;" cf. Skt. deś- "to show, point out;" PIE *deik- "to show" (cf. Gk. deiknumi "to show," dike "manner, custom;" L. dicere "to utter, say;" O.H.G. zeigon, Ger. zeigen "to show;" O.E. teon "to accuse," tæcan "to teach") + -i noun suffix.
2) Bâzdisidan infinitive from bâzdisi, as above.

refract
  شکستن   
šekastan (#)

Fr.: réfracter   

To alter the course of a wave of light, sound, etc. when the wave crosses the boundary between this medium and another through which it travels at a different speed.

From L. refractus, p.p. of refringere, → refraction.

Verb of šekast, → refraction.

refracted ray
  پرتو ِ شکسته   
partow-e šekasté (#)

Fr.: rayon réfracté   

A → light ray that undergoes a change of velocity and direction, as a result of interaction with the material medium in which it travels.

reflect; → ray.

refracting
  شکست؛ شکست‌گر   
šekast; šekastgar

Fr.: réfraction; à réfraction   

1) The action or result of the verb → refract.
2) Participial adjective of → refract.

From → refract + → -ing.

refracting prism
  منشور ِ شکست‌گر   
manšur-e šekastgar (#)

Fr.: prisme réfractant   

A prism that is used as a dispersing element in a spectrograph.

refracting; → prism.

refracting telescope
  تلسکوپ ِ شکستی، دوربین ِ ~   
teleskop-e šekasti (#), durbin-e ~ (#)

Fr.: lunette astronomique   

A telescope in which an image is formed by the refraction of light through a lens or lens system.

refracting; → telescope.

refraction
  شکست   
šekast (#)

Fr.: réfraction   

1) Optics: The change of direction which a beam of light undergoes as it enters a medium of different → refractive index.
2) Acoustics: The change in direction in sound waves on reaching the boundary between two media.
3) Seismology: The bending of a seismic wave as it enters a material of different density.

From L.L. refractionem (nominative refractio) "a breaking up," from L. refractus, p.p. of refringere "to break up," from re- "back" + combining form of frangere "to break," from PIE base *bhreg- "to break" (cf. Goth. brikan, O.E. brecan "to break;" Lith. brasketi "crash, crack").

Šekast, past stem of šekastan "to break, split;" Mid.Pers. škastan "to break;" Av. scind-, scand "to beak, cleave;" Proto-Iranian *skand- "to break, cleave;" PIE sken- "to cut off."

refractive index
  دیشن ِ شکست   
dišan-e šekast

Fr.: indice de réfraction   

Of any optical medium, the ratio of the → speed of light in vacuum (c) to that in the medium (v): n = c/v. The refractive index for vacuum, by definition, is 1. The refractive index of air is 1.00029 at standard temperature (25 °C) and pressure (1 atm). The refractive index of a medium depends on the wavelength of refracted wave. With light waves, n increases as the wavelength decreases. → Snell's law can be used to derive n. Same as → index of refraction.

Refractive, pertaining to → refraction; → index.

refractor
  شکست‌گر   
šekastgar (#)

Fr.: réfracteur   

Same as → refracting telescope.

Agent noun of refract, → refraction.

refractory
  سرکش، دیرگداز   
sarkeš, dirgodâz

Fr.: réfractaire   

A substance that has a high → melting point. It is therefore resistant to treatment and not easily melted or worked. The opposite of → volatile.

From refract, → refraction + adj. suffix -ory.

Sarkeš "refractory, disobedient, rebellious, stubborn," literally "withdrw, remove head," from sar "head" (variants soru, sorun "horn," karnâ "a trumpet-like wind instrument," variant sornâ "a wind instrument;" Mid.Pers. sar "head," sru "horn;" Av. sarah- "head," srū- "horn, nail;" cf. Skt. śiras- "head, chief;" Gk. kara "head," karena "head, top," keras "horn;" L. cornu "horn," cerebrum "brain;" P.Gmc. *khurnaz (Ger. Horn, Du. horen; cognate with E. horn, as above, from PIE *ker- "head, horn;" O.E. horn "horn of an animal," also "wind instrument;" E. horn); PIE base *ker- "head, horn, top, summit") + keš present stem of kešidan, kašidan "to draw; withdraw, remove" (dialectal Yaqnavi xaš "to draw," Qomi xaš "streak, stria, mark," Lori kerr "line;" Av. karš- "to draw; to plow," karša- "furrow;" Proto-Iranian *kerš-/*xrah- "to draw, plow;" cf. Skt. kars-, kársati "to pull, drag, plow;" Gk. pelo, pelomai "to move, to bustle;" PIE base kwels- "to plow").
Dirgodâz, literally "melting slowly, with delay," from dir "slowly, tardily; late" (Mid.Pers. dêr, variants dagr, drâz "long;" (Mod.Pers. derâz "long," variant Laki, Kurdi derež); O.Pers. darga- "long;" Av. darəga-, darəγa- "long," drājištəm "longest;" cf. Skt. dirghá- "long (in space and time);" L. longus "long;" Gk. dolikhos "elongated;" O.H.G., Ger. lang; Goth. laggs "long;" PIE base *dlonghos- "long") + godâz-, godâxtan "to melt" (Mid.Pers. vitâxtan, vitâcitan "to melt," from Av. vi-taxti- "flowing away, melting," from vi- "apart, away from, out" (O.Pers. viy- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + tak- "to run, to flow," taciāp- "flowing water," tacinti (3pl.pers.act.) "to flow," tacar- "course," tacan "current, streaming;" Mod.Pers. tâz-, tâxtan "to run; to hasten; to assault," tâzi "swift (greyhound)," tak "running, rush;" Mid.Pers. tâz-, tâxtan "to flow, to cause to walk," tc- "to flow, to walk," tag "running, attack," tâzig "swift, fast;" Khotanese ttajs- "to flow, to walk;" cf. Skt. tak- "to rush, to hurry," takti "runs;" O.Ir. tech- "to flow;" Lith. teketi "to walk, to flow;" O.C.S. tešti "to walk, to hurry;" Tokharian B cake "river;" PIE base *tekw- "to run; to flow").

refusal
  نژن   
nežan

Fr.: refus   

An act or instance of refusing.

refuse; → -al.

Nežan, from ne- "down, below," → ni-, + žan variant of zan present stem of zadan "to hit, strike," variants Zazaki jinen-, Gazi žen-/žent "to beat, hit," Baluchi jat/jan- "to strike, hit," Awromani žanây/-žan- "to shut (the door)," Pashto -žan "to chop, mince," → beat.

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