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: 464
Le Chatelier's Principle
  پروز ِ لو شاتولیه   
parvaz-e Le Chatelier

Fr.: principe de Le Chatelier   

A change in one of the variables (such as temperature, pressure, and concentration of various species) that describe a system at equilibrium produces a shift in the position of the equilibrium that counteracts the effect of this change.

Named after the French chemist and engineer Henry Louis Le Chatelier (1850-1936); → principle.

lead
  سرب   
sorb (#)

Fr.: plomb   

A metallic chemical element; symbol Pb (L. plumbum, of unknown origin). Atomic number 82; atomic weight 207.2; melting point 327.502°C; boiling point about 1,740°C. One of the oldest metals used by humanity, because of its relatively low melting point.

O.E. lead, from W.Gmc. *loudhom (cf. O.Fris. lad, M.Du. loot "lead," Ger. Lot "weight, plummet").

Sorb, from Mid.Pers. srub "lead;" Av. sru- "lead."

leader spot
  لکه‌ی ِ پیشرو   
lakke-ye pišrow (#)

Fr.: tache de tête   

In a → sunspot group, the first spot to form in the direction of rotation and the last to disappear. It is the largest, the strongest in magnetic intensity, and the closest to the solar equator among the group sunspots. See also → follower spot.

From M.E. leder(e), O.E. lædan "cause to go with one, lead," from W.Gmc. *laithjan (cf. O.S. lithan, O.N. liða "to go," O.H.G. ga-lidan "to travel," Goth. ga-leiþan "to go"); → spot.

Lakké, → spot; pišrow "leader, forerunner," from piš "in front, forward, before" (Mid.Pers. pêš "before, earlier;" O.Pers. paišiya "before; in the presence of") + row "going," present stem of raftan "to go, elapse, glide by, depart" (Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack").

leaf
  برگ   
barg (#)

Fr.: feuille   

One of the organs, usually green and flat, growing from the side of a stem or branch or direct from the root of a tree or plant. A leaf constitutes a unit of the foliage, and functions primarily in food manufacture by → photosynthesis.

M.E. leef, lef; O.E. leaf; cf. O.S. lof, O.N. lauf, O.Fris. laf, Du. loof, O.H.G. loub, Ger. Laub.

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."

leap
  اندرهلی   
andarheli

Fr.: bissextile, intercalaire   

In a calendar, having an extra day or month inserted.

O.E. hleapan "to jump, run, leap" (cf. O.S. hlopan, O.N. hlaupa, O.Fris. hlapa, Du. lopen, Ger. laufen "to run," Goth. us-hlaupan "to jump up"), of uncertain origin, with no known cognates beyond Germanic. The noun is O.E. hlyp (Anglian *hlep). Noun in leap year, so called from its causing fixed festival days to "leap" ahead one day in the week.

Andarheli, from andarhel, verbal noun of andarhelidan, andarheštan "to insert," from andar-inter- + helidan, heštan "to place, put" from Mid.Pers. hištan, hilidan "to let, set, leave, abandon;" Parthian Mid.Pers. hyrz; O.Pers. hard- "to send forth;" ava.hard- "to abandon;" Av. harəz- "to discharge, send out; to filter," hərəzaiti "releases, shoots;" cf. Skt. srj- "to let go or fly, throw, cast, emit, put forth;" Pali sajati "to let loose, send forth."

leap day
  روز ِ اندرهلی   
ruz-e andarheli

Fr.: jour intercalaire   

The extra day added to a solar calendar (e.g. Gregorian, Iranian) in a leap year.

leap; → day.

leap month
  ماه ِ اندرهلی   
mâh-e andarheli

Fr.: mois intercalaire   

An intercalary month employed in some calendars to preserve a seasonal relationship between the Lunar and Solar cycles. → embolismic month.

leap; → month.

leap second
  ثانیه‌ی ِ اندرهلی   
sâniyeh-ye andarheli

Fr.: seconde intercalaire   

A one-second added between 60s and 0s at announced times to keep the Coordinated Universal Time (UTC), counted by atomic clocks, within 0s.90 of mean solar time (UT1). Generally, leap seconds are added at the end of June or December.

leap; → second.

leap year
  سال ِ اندرهلی   
sâl-e andarheli

Fr.: année bissextile   

In solar calendars the year that contains 366 days, instead of 365, in order to keep the calendar in pace with the real solar time.

leap; → year.

least
  کوچکترین، کمترین   
kucektarin, kamtarin

Fr.: moindre, plus petit   

Smallest in size, amount, degree, etc.

From M.E. leest(e), O.E. læst, læsest "smallest" (superlative of læs "smaller, less").

Kucaktarin, kamtarin, superlatives of kucak and kam, → small.

least common multiplier (LCM)
  کوچکترین بستاگر ِ همدار   
kucektarin bastâgar-e hamdâr

Fr.: plus petit commun multiple   

Of two or more → integers, the smallest positive number that is divisible by those integers without a remainder.

least; → common; → multiplier.

least squares
  کوچکترین چاروش‌ها   
kucaktarin cârušhâ

Fr.: moindres carrés   

Any statistical procedure that involves minimizing the sum of squared differences.

least; → square.

least-squares fit
  سز ِ کوچکترین چاروش‌ها   
saz-e kucaktarin cârušhâ

Fr.: ajustement moindres carrées   

A fit through data points using least squares.

least squares; → fit.

leave
  ۱) پریژیدن؛ ۲) پریژ   
1) parižidan; 2) pariž

Fr.: 1) quitter; 2) congé, permission   

1a) Go away from.
1b) To let remain or have remaining behind after going, disappearing, ceasing, etc.
2a) Permission to be absent, as from work or military duty.
2b) The time this permission lasts (Dictionary.com).

M.E. leven, from O.E. laefan "to allow to remain in the same state or condition" (cf. O.Saxon farlebid "left over;" Ger. bleiben "to remain") ultimately from PIE *leip- "to stick, adhere;" also "fat," from which the cognates: Gk. lipos "fat;" O.E. lifer "liver," → life.

Parižidan, on the model of Sariqoli barēzj "leavings;" Yaghnobi piraxs- "to stay behind, remain;" ultimately from Proto-Ir. *apa-raic-, from *raic- "to abandon, leave;" cf. Av. raēc- "to leave, let" (Cheung 2006), → heritage.

Leavitt law
  قانون ِ لویت   
qânun-e Leavitt

Fr.: loi de Leavitt   

Same as the → period-luminosity relation.

Named after Henrietta Swan Leavitt (1868-1921), American woman astronomer, who discovered the relation between the luminosity and the period of → Cepheid variables (1912); → law.

Leclanché cell
  پیل ِ لوکلانشه   
pil-e Leclanché (#)

Fr.: pile de Leclanché   

A → primary cell in which the anode is a rod of carbon and the cathode a zinc rod both immersed in an electrolyte of ammonia plus a depolarizer.

Named after the inventor Georges Leclanché (1839-1882), a French chemist, → cell.

Leda
  لدا   
Ledâ (#)

Fr.: Léda   

1) The ninth of Jupiter's known satellites and the smallest. It is 16 km in diameter and has its orbit at 11 million km from its planet. Also called Jupiter XIII, it was discovered by Charles Kowal (1940-), an American astronomer, in 1974.
2) An asteroid, 38 Leda, discovered by J. Chacornac in 1856.

In Gk. mythology, Leda was queen of Sparta and the mother, by Zeus in the form of a swan, of Pollux and Helen of Troy.

Ledoux's criterion
  سنجیدار ِ لو‌دو   
sanjidâr-e Ledoux

Fr.: critère de Ledoux   

An improvement of → Schwarzschild's criterion for convective instability, which includes effects of chemical composition of the gas. In the Ledoux criterion the gradient due to different molecular weights is added to the adiabatic temperature gradient.

After the Belgian astrophysicist Paul Ledoux (1914-1988), who studied problems of stellar stability and variable stars. He was awarded the Eddington Medal of the Royal Astronomical Society in 1972 (Ledoux et al. 1961 ApJ 133, 184); → criterion.

left
  چپ   
cap (#)

Fr.: gauche   

Of, pertaining to, or located on or toward the west when somebody or something is facing north. Opposite of → right.

M.E. left, lift, luft, O.E. left, lyft- "weak, idle," cf. Ger. link, Du. linker "left," from O.H.G. slinc, M.Du. slink "left," Swed. linka "limp," slinka "dangle."

Cap "left," from unknown origin.

left-hand rule
  رزن ِ دست ِ چپ   
razan-e dast-e cap

Fr.: règle de la main gauche   

See → Fleming's rules.

left; → hand; → rule.

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