# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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 lambert   لامبرت   lambertFr.: lambert   A centimeter-gram-second (cgs) unit of luminance (or brightness) equal to 1/π candle per square centimeter. Physically, the lambert is the luminance of a perfectly diffusing white surface receiving an illuminance of 1 lumen per square centimeter.Johann Heinrich Lambert (1728-1777), German scientist and mathematician; → law. Lambert's cosine law   قانون ِ کوسینوس ِ لامبرت   qânun-e cosinus-e LambertFr.: loi en cosinus de Lambert   The intensity of the light emanating in any given direction from a perfectly diffusing surface is proportional to the cosine of the angle between the direction and the normal to the surface. Also called → Lambert's law.→ lambert; → cosine; → law. Lambert's law   قانون ِ لامبرت   qânun-e LambertFr.: loi de Lambert   Same as → Lambert's cosine law.→ lambert; → law. Lambertian disk   گرده‌ی ِ لامبرتی، دیسک ِ ~   gerde-ye Lamberti, disk-e ~Fr.: disque lambertien   A → planetary or → satellite disk with → Lambertian surface. Such a disk has the same → surface brightness at all angles.→ lambert; → disk. Lambertian surface   رویه‌ی ِ لامبرتی   ruye-ye LambertiFr.: surface lambertienne   A surface whose → luminous intensity obeys → Lambert's cosine law. Such a source has a → reflectance that is uniform across its surface and uniformly emits in all directions from all its points. It appears equally bright from all viewing directions. Lambertian surface is a very useful concept for the approximation of radiant power transfer.→ lambert; → surface. lament   ۱) شکوه؛ ۲) شکویدن   1) šekvé (#); šekvidanFr.: 1) lamentation, grief; 2) se lamenter   1a) A real or imagined cause for → complaint, especially unfair treatment. 1b) A feeling of resentment over something believed to be wrong or unfair. 2) To feel or express sorrow or regret for; to mourn for or over (OxfordDictionaries.com).M.E., from M.Fr. lament and directly from L. lamentum "a wailing, moaning, weeping" from lamentum "a wailing," from PIE root *la- "to shout, cry."Šekvé, Pers. construction from Ar. šakvâ "complaint." lamina   ورقه   varaqé (#)Fr.: lame, lamina   A thin plate, layer, or flake.From L. lamina "thin plate or layer, leaf."Varaqé "sheet, plate," from varaq "a leaf of tree or of paper," from Ar. waraq, from Pers. barg "leaf" (Tabari, Gilaki valg, balg; Kurd. belg, balk, Semnâni valg); Mid.Pers. warg "leaf;" Av. varəka- "leaf;" cf. Skt. valká- "bark, bast, rind;" Russ. volokno "fibre, fine combed flax." laminar   ورقه‌ای   varaqe-yiFr.: laminaire   Composed of, or arranged in, laminae, sheets.→ lamina + → -ar. laminar boundary layer   لایه‌ی ِ کرانی ِ ورقه‌ای   lâye-ye karâni-ye varaqe-yiFr.: Couche limite laminaire   In a fluid flow, layer next to a fixed boundary. The fluid velocity is zero at the boundary but the molecular viscous stress is large because the velocity gradient normal to the wall is large. → turbulent boundary layer.→ laminar; → boundary; → layer. laminar flow   تچان ِ ورقه‌ای   tacân-e varaqe-yiFr.: écoulement laminaire   A flow in which the particles of fluid are moving orderly, and in which adjacent layers or laminas glide smoothly over another with little mixing between them. A laminar flow may rapidly transform into a → turbulent flow for large → Reynolds numbers.→ laminar; → flow. laminar sublayer   زیرلایه‌ی ِ ورقه‌ای   zirlâye-ye varaqe-yiFr.: sous-couche laminaire   A layer in which the fluid undergoes smooth, nonturbulent flow. It is found between any surface and a turbulent layer above.→ laminar; sublayer, from → sub- + → layer. lamp   لامپ، چراغ   lâmp (#), cerâq (#)Fr.: lampe   Any of various devices producing artificial light, as by electricity, gas, or oil.From O.Fr. lampe, from L. lampas, from Gk. lampas "torch, lamp, beacon, meteor, light," from lampein "to shine," from PIE base *lap- "to shine" (cf. Lith. lope "light," O.Ir. lassar "flame").Lâmp, loanword from Fr., as above. Cerâq "lamp" (variants Kurd. cira, cerâh, Laki cerâx, Zâzâ cərâ, cərâx "lamp, candle," Shughni cirow, cirâw, cərêγ "candle, lamp"); Mid.Pers. cirâq "lamp," related to foruq "light," afruxtan "to light, kindle," rowšan "bright, clear," rowzan "window, aperture;" ruz "day;" Mid.Pers. rôšn "light; bright, luminous," rôc "day;" O.Pers. raucah-rocânak "window;" O.Pers. raocah- "light, luminous; daylight;" Av. raocana- "bright, shining, radiant;" akin to Skt. rocaná- "bright, shining," roka- "brightness, light;" Gk. leukos "white, clear;" L. lux "light" (also lumen, luna); Fr. lumière; E. light; O.E. leoht, leht, from W.Gmc. *leukhtam (cf. O.Fris. liacht, M.Du. lucht, Ger. Licht), from PIE *leuk- "light, brightness." land   خشکی، زمین   xoški (#), zamin (#)Fr.: terre   Any part of the earth's surface not covered by a body of water.M.E., from O.E. land, lond, "ground, soil, territory;" PIE base *lendh- "land, heath" (cf. O.N., O.Fris. Du., Ger., Goth. land; O.Ir. land; Welsh llan "enclosure, church," Breton lann "heath," source of Fr. lande; O.C.S. ledina "waste land, heath," Czech lada "fallow land").Xoški, from xošk, → dry, + noun suffix -i; zamin "land, → earth." land breeze   نسیم ِ خشکی   nasim-e xoški (#)Fr.: brise de terre   A coastal breeze blowing from land to sea after sunset, caused by the temperature difference when the sea surface is warmer than the adjacent land. The warmer air above the water continues to rise, and cooler air from over the land replaces it, creating a breeze.Land, → lander; → breeze.Xoški "land," from xošk "dry;" Mid.Pers. xušk "dry;" O.Pers. uška- "mainland;" Av. huška- "dry;" cf. Skt. śuska- "dry, dried out;" Gk. auos "dry, dried up;" O.E. sēar "dried up, withered;" Lith. sausas "dry, barren." Landau damping   میرایی ِ لانداؤ   mirâyi-ye LandauFr.: amortissement de Landau   The process wherein a → plasma gains energy at the expense of the → Langmuir wave. In the presence of the → Landau resonance, the particles in resonance moving slightly faster than the wave lose energy, while those moving slightly slower will gain energy. Since the Maxwellian distribution is decreasing with velocity, in a Maxwellian plasma, near the Landau resonance, there are more particles at lower velocities than at higher velocities. Also called collisionless damping.Lev Landau (1908-1968), a prominent Soviet physicist, 1962 Nobel Prize in Physics for his development of a mathematical theory of → superfluidity; → damping. Landau level   تراز ِ لانداؤ   tarâz-e LandauFr.: niveau de Landau   The → energy level which can be occupied by a → free electron in a → magnetic field.→ Landau damping; → level. Landau resonance   باز‌آوایی ِ لانداؤ   bâzâvâyi-ye LandauFr.: résonance de Landau   For parallel propagating → electrostatic waves in a → plasma, the → resonance which occurs when the particle velocity equals the parallel phase velocity of the wave. Landé factor   کروند ِ لانده   karvand-e LandéFr.: facteur de Landé   The constant of proportionality relating the separations of lines of successive pairs of adjacent components of the levels of a spectral multiplet to the larger of the two J-values for the respective pairs. The interval between two successive components J and J + 1 is proportional to J + 1.After Alfred Landé (1888-1976), a German-American physicist, known for his contributions to quantum theory; → facteur. lander   زمین‌نشین   zamin-nešinFr.: atterrisseur   A → space probe designed to land on a → planet or other solid → celestial body.→ land; → -er. Lane-Emden equation   هموگش ِ لین-امدن   hamugeš-e Lane-EmdenFr.: équation de Lane-Emden   A second-order nonlinear → differential equation that gives the structure of a → polytrope of index n.Named after the American astrophysicist Jonathan Homer Lane (1819-1880) and the Swiss astrophysicist Robert Emden (1862-1940); → equation