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: 415
focal plane
  هامن ِ کانونی   
hâmon-e kânuni

Fr.: plan focal   

A plane at right angles to the principal axis of a lens or mirror on which the best image is formed.

focal; → plane.

focal point
  نقطه‌ی ِ کانونی   
noqte-ye kânuni

Fr.: point focal   

Same as → focus.

focal; → point.

focal ratio
  وابر ِ کانونی   
vâbar-e kânuni

Fr.: rapport focal   

The ratio of the → focal length of a reflecting surface or lens to its effective diameter, i.e. to its → aperture. The smaller the focal ratio, the smaller the image scale and the more luminous the image for a given aperture.

focal; → ratio.

focal reducer
  کاهنده‌ی ِ کانونی، باز‌هازنده‌ی ِ ~   
kâhande-ye kânuni, bâzhâzande-ye ~

Fr.: réducteur focal   

An optical component or system for changing the image scale of a telescope to achieve a better match between the → seeing disk and the → pixel size.

focal; → reducer.

focus
  ۱) کانون؛ ۲) کانونیدن   
1) kânun; 2) kânunidan

Fr.: 1) foyer; 2) focaliser   

1) (n.) A point where parallel light rays from an object are gathered together by a lens or a concave mirror. It is the place where the clearest image of a distant object forms. Also called focal point. See also → focal distance.
2) (v.) To adjust the eyepiece or objective of a telescope so that the image is clearly seen by the observer.

From L. focus "hearth, fireplace," of unknown origin,

Kânun "hearth, fireplace."

focused
  کانونیده   
kânunidé

Fr.: focalisé   

Of an optical system, being in focus or brought into focus; adjusted to produce a clear image.

Past participle of → focus.

focusing
  کانونش   
kânuneš

Fr.: focalisation   

The act of bringing into focus.

Noun of → focus.

fog
  مه   
meh (#)

Fr.: brouillard   

A mass or layer of suspended water droplets or ice crystals near the surface of the earth, reducing visibility.

From Dan. fog "spray, shower, snowdrift," related to O.N. fok "snow flurry."

Meh "fog" (variants miq, mož, Tabari miyâ, Lori/Laki (kara) mozy, Ossetic mig/megæ), from Mid.Pers. mēq "cloud, mist," Av. mēγa- "cloud;" cf. Skt. meghá- "cloud, overcast weather;" Gk. omikhle "mist;" Lith. miglà "mist, haze;" PIE base *mighlā- "cloud."

fogbow
  مه‌کمان   
meh-kamân

Fr.: arc blanc   

A large, faintly colored, circular arc formed by light (usually sunlight) falling on cloud or fog. Also called → cloudbow.

fog; → bow.

Fokker-Planck equation
  هموگش ِ فوکر-پلانک   
hamugeš-e Fokker-Planck

Fr.: équation de Fokker-Planck   

A modified form of → Boltzmann's equation allowing for collision terms in an approximate way. It describes the rate of change of a particle's velocity as a result of small-angle collisional deflections.

After Dutch physicist Adriaan Fokker (1887-1972) and the German physicist Max Planck (1858-1947); → equation.

folk
  پلگ   
palg

Fr.: gens, les gens   

1) Usually, folks. (used with a plural verb) people in general.
2) (used with a plural verb) people as the carriers of culture, especially as representing the composite of social mores, customs, forms of behavior, etc., in a society (Dictionary.com).

M.E.; O.E. folc; cognate with O.Sax., O.Norse folk, O.H.G. folk (Ger. Volk).

Palg, from (Pashto) parrk "group of people," with variants: (Dehxodâ) parré "group of people; a circular disposition of troops for hunting or other purposes; a rank or file of soldiers;" (Lori, Torbart-Heydariye-yi, Qomi) borr "group of people, crowd;" (Qomi) borré; (Laki) berr "group of people;" (Qâyeni) bor "group, flock, herd;" (Kurd. Kurmanji) âpora "crowd;" transformation of -r- into -l- (as por = bol, → poly-) in Tabari bəlik, əllik "herd, flock;" ultimately from Proto-Ir. *paraka-, from *par- "to fill;" cf. Av. pər- "to fill, stuff with," pouru- "full, much, many;" O.Pers. paru- "much, many;" Pers. anbâr "ricks, storehouse," por, bol "full, much, many;" PIE *pel- "to fill;" → population.

folklore
  پلگوار   
palgvâr

Fr.: folkolre   

The traditional beliefs, legends, customs, etc., of a people; lore of a people (Dictionary.com).

Coined by English scholar and antiquary William John Thoms (1803-1885), from → folk, + lore "traditional knowledge or belief," from M.E., O.E. lar cognate with Du. leer, Ger. Lehre "teaching," E. learn.

Palgvâr, literally "customs of people," from palg, → folk, + vâr "custom, rule, law" (Dehxodâ).

follow-up observation
  نپاهش ِ پیگیر   
nepâheš-e peygir

Fr.:   

An observation which expands previous observations and aims at obtaining complementary data in particular with other telescopes/instruments.

Follow-up, from follow, from O.E. folgian, fylgan "to follow, pursue," from W.Gmc. *fulg- (cf. O.Fris. folgia, M.Du. volghen, Ger. folgen "to follow") + up, O.E. up, uppe (cf. Du. op, Ger. auf "up, upward"), from PIE base *upo "up from below;" cf. O.Pers./Av. upā; Skt. úpa; Gk. hypo; L. sub, → hypo-; → observation.

Nepâheš, → observation; peygir, from pey "after; step," related to "foot, step, track," → foot, + gir present stem of gereftan "to take, seize" (Mid.Pers. griftan, Av./O.Pers. grab- "to take, seize," cf. Skt. grah-, grabh- "to seize, take," graha "seizing, holding, perceiving," M.L.G. grabben "to grab," from P.Gmc. *grab, E. grab "to take or grasp suddenly;" PIE base *ghrebh- "to seize").

follower spot
  لکه‌ی ِ پیرو   
lake-ye peyrow

Fr.: tache de queue   

A → sunspot that follows the → leader spot. Sunspots tend to appear in groups consisting of one leader and several follower spots. The leader and the follower spots having opposite polarities.

Agent noun of follow, from O.E. folgian, fylgan "to follow, pursue," from W.Gmc. *fulg- (cf. O.Fris. folgia, M.Du. volghen, Ger. folgen "to follow").

Laké, → spot; peyrow "follower," from pey "step; after," related to "foot, step, track," → foot, + row "going; which goes," present stem of raftan "to go, walk, proceed," Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack."

Fomalhaut (α PsA)
  فم‌الحوت، ماهی‌دهان   
famelhut (#), mâhidahân

Fr.: Fomalhaut   

The brightest star (V = 1.17) in the constellation → Piscis Austrinus. Fomalhaut is a white A3 main-sequence star about 25 light-years away. It is encircled by a dust belt (→ debris disk) of about 25 A.U. wide at a radial distance of about 140 A.U.

From Ar. Fam al-Hut (فم‌الحوت) "the fish's mouth," from fam "mouth" + hut "fish."

Famelhut, from Ar. as above; Mâhidahân, from mâhi "fish," from Mid.Pers. mâhik; Av. masya-; cf. Skt. matsya-, Pali maccha- + dahân "mouth;" Mid.Pers. dahân, from Av. zafan-, zafar- "mouth (of Ahrimanic beings)."

font
  ریختار، فونت   
rixtâr (#), font

Fr.: police, fonte   

An assortment or set of type or characters all of one style and sometimes one size (Merriam-Webster.com).

From M.Fr. fonte "act of founding, casting," from fondre "to melt," so called because all the letters in a given set were cast at the same time (etymonline.com).

Rixtâr, from rixtan "to cast, to pour," → morphology.

foot
  پا   
pâ (#)

Fr.: pied   

1) The terminal part of the vertebrate leg upon which an individual stands.
2) Something resembling a foot in position or use.

M.E., from O.E. fot; cf. O.S. fot, O.N. fotr, Du. voet, O.H.G. fuoz, Ger. Fuß, Goth. fotus "foot;" cognate with Pers. pâ, pây, as below.

"foot;" Mid.Pers. pâd, pây; Khotanese fad; Av. pad- "foot;" cf. Skt. pat; Gk. pos, genitive podos; L. pes, genitive pedis; E. foot, as above; PIE *pod-/*ped-.

Forbes effect
  اسکر ِ فوربز   
oskar-e Forbes

Fr.: effet Forbes   

Increased reddening and monochromaticity of light as the path length in the air increases.

After the Scottish physicist James David Forbes (1809-1868); → effect.

forbidden
  بژکم   
bažkam (#)

Fr.: interdit   

1) General: Not allowed; prohibited.
2) Physics: Involving a change in → quantum numbers that is not permitted by the → selection rules, → forbidden transition.

Past participle of forbid, from O.E. forbeodan, from for- "against" + beodan "to command" (O.E. biddan"to beg, ask, demand;" cf. Ger. bitten "to ask"); cf. Du. verbieden, O.H.G. farbiotan, Ger. verbieten.

Bažkam in classical Persian dictionaries "a keeping back, a preventing," from Av. paitigam- "to prevent," from paiti- "opposite, against, back, in return" (O.Pers. paity "agaist, back, opposite to, toward, face to face, in front of;" Mod.Pers. variants pâd- (→ anti-); cf. Skt. práti "opposite, against, again, back, in return, toward;" Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti) + gam- "to come; to go," jamaiti "goes;" O.Pers. gam- "to come; to go;" Mod./Mid.Pers. gâm "step, pace," âmadan "to come" (cf. Skt. gamati "goes;" Gk. bainein "to go, walk, step;" L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come; PIE root *gwem- "to go, come").

forbidden band
  باند ِ بژکم   
bând-e bažkam

Fr.: bande interdite   

In → solid state physics, a range of → energy levels which is not attained by any electrons in a → crystal. In the energy level diagram forbidden bands appear as gaps between → allowed bands.

forbidden; → band .

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