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: 13176 Search : far
law of cosines
  قانون ِ کوسینوس‌ها   
qânun-e kosinushâ

Fr.: loi des cosinus   

An expression that for any triangle relates the length of a side to the cosine of the opposite angle and the lengths of the two other sides. If a, b, and c are the sides and A, B, and C are the corresponding opposites angles: a2 = b2 + c2 - 2bc cos A; b2 = c2 + a2 - 2ca cos B; c2 = a2 + b2 - 2ab cos C.

law; → cosine.

law of excluded middle
  قانون ِ میانی سکلانده   
qânun-e miyâni soklândé

Fr.: principe du milieu exclu   

Same as → principle of excluded middle.

law; → exclude; → middle.

law of identity
  قانون ِ ایدانی   
qânun-e idâni

Fr.: principe d'identité   

Same as → principle of identity.

law; → identity.

law of inertia
  قانون ِ لختی   
qânun-e laxti (#)

Fr.: loi d'inertie   

Same as → Newton's first law. The → reference frames to which the law applies are called → inertial frames.

law; → inertia.

law of non-contradiction
  قانون ِ ناپادگویی   
qânun-e nâpâdguyi

Fr.: principe de non-contradiction   

Same as → principle of non-contradiction.

law; → non-; → contradiction.

law of reflection
  قانون ِ بازتاب   
qânun-e bâztâb (#)

Fr.: loi de réflexion   

One of the two laws governing reflection of light from a surface: a) The → incident ray, normal to surface, and reflected ray lie in the same plane. b) The → angle of incidence (with the normal to the surface) is equal to the → angle of reflection.

law; → reflection.

law of refraction
  قانون ِ شکست   
qânun-e šekast (#)

Fr.: loi de réfraction   

One of the two laws governing → refraction of light when it enters another transparent medium: a) The → incident ray, normal to the surface, and refracted ray, all lie in the same plane. b) → Snell's law is satisfied.

law; → refraction.

law of sines
  قانون ِ سینوس‌ها   
qânun-e sinushâ

Fr.: loi des sinus   

In any triangle the sides are proportional to the sines of the opposite angles: a/sin A = b/sin B = c/sin C, where A, B, and C are the three vertices and a, b, and c are the corresponding sides.

law; → sine.

lawrencium
  لاؤرنسیوم   
lawrensiom (#)

Fr.: lawrencium   

An artificially produced → radioactivechemical element; symbol Lr (formerly Lw). → Atomic number 103; → atomic weight of most stable isotope 262; → melting point about 1,627°C; → boiling point and → specific gravity unknown; → valence +3. The longest half-life associated with this unstable element is 3.6 hour 262Lr. Credit for the first synthesis of this element in 1971 is given jointly to American chemists from the University of California laboratory in Berkeley under Albert Ghiorso and the Russian team at the Joint Institute for Nuclear Reactions lab in Dubna, under Georgi N. Flerov.

Named the American physicist Ernest 0. Lawrence (1901-1958), who developed the → cyclotron, + → -ium.

laws of dynamics
  قانون‌های ِ توانیک   
qânunhâ-ye tavânik

Fr.: lois de dynamique   

The three basic laws of → dynamics which were first formulated by Isaac Newton in his classical work "Mathematical Principles of Natural Philosophy" published in 1687. → Newton's first law of motion; → Newton's second law of motion; → Newton's third law of motion.

law; → dynamics.

layer
  لایه   
lâyé (#)

Fr.: couche   

A thickness of some material laid on or spread over a surface.

From M.E. leyer, legger + -er. The first element from layen, leggen "to lay," from O.E. lecgan; cf. Du. leggen; Ger. legen; O.N. legja; Goth. lagjan

Lâyé "layer," from lâ, lây "fold" + nuance suffix of nouns.

Layzer-Irvine equation
  هموگش ِ لیزر-آیروین   
hamugeš-e Layzer-Irvine

Fr.: équation de Layzer-Irvine   

The ordinary Newtonian energy conservation equation when expressed in expanding cosmological coordinates. More specifically, it is the relation between the → kinetic energy per unit mass associated with the motion of matter relative to the general → expansion of the Universe and the → gravitational potential energy per unit mass associated with the departure from a homogeneous mass distribution. In other words, it deals with how the energy of the → Universe is partitioned between kinetic and potential energy. Also known as → cosmic energy equation. In its original form, the Layzer-Irvine equation accounts for the evolution of the energy of a system of → non-relativistic particles, interacting only through gravity, until → virial equilibrium is reached. But it has recently been generalized to account for interaction between → dark matter and a homogeneous → dark energy component. Thus, it describes the dynamics of local dark matter perturbations in an otherwise homogeneous and → isotropic Universe (P. P. Avelino and C. F. V. Gomes, 2013, arXiv:1305.6064).

W. M. Irvine, 1961, Ph.D. thesis, Harvard University; D. Layzer, 1963, Astrophys. J. 138, 174; → equation.

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.

<< < -es -it -sc 201 951 abe abs abs aca acc acc aco act ada adh ado aer aft air Alf alg alk alp Alt alt amb ana And ang ani ann ant ant ant apo app app Apu arc arg Arn art ass ast ast ast atm ato att aur aut avo azi bac bal bar bar bat Bea Bel bet bia big bin bio Bir bla bla blo Blu bol Boo bou box bre Bri bro bur cal cal Can cap car Car cat cau cel cen cen cha Cha cha che Chi chr cir cir civ cla clo clo CMB coa coe coh col col col com com com com com com com com Com con con con con con con con con con con con con coo cor cor cor Cos cos cos cou cou cra cri cro cry cul cur cyc D l dar dat day dea dec dec dec def def deg Del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis diu dog Dop dou Dra Dsc dus dwa dyn Dys Ear ecc eco edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ eru eth Eur eve exa exc exe exi exo exp ext ext ext fab fai Fan fea fem fer fie fil fir fir fla fli flu foc for for for fra fre fre fri fun fuz gal gal gal Gam gau Gau gen geo geo geo geo Gib glo gov gra gra gra gra gre gro Gui H-a hal Ham har Hay hea hei hel Hel her het hie hig hoa hom hor hot Hub Hug hur hyd hyd hyl hyp ice ide ima ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv inv ion iro Isl iso iso Jab jet Jov Jup Kar Kep kil Kip Kra Lag Lam Lan Lar las law lea Leg Leo lev lig lim lin lin lin lit loc loc log Lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal map mas mas mat Mau mea mea med Men mer Mes Met met mic mic Mie mil min Mir mix mod mol mom Moo mor mov mul mur n-b nan nat nea neg Ner neu new New NGC noc nom non non nor nor nuc nuc nul nut obj obl obs occ oct off old one ope opp opt opt orb ord org Ori osc oth ove Owl P-s Pal par par par par Pas pat pec pen per per per per per Pha pha pho pho pho phy pie pix Pla pla pla pla Pli Poi pol pol pol pol por pos pos pow pre pre pre pre pri pri pri pro pro pro pro pro pro pro pub pul pyc qua qua qua qua qui rad rad rad rad rad rad rai ran rar Ray rea Rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot rur S5- Sal sat sca sca Sch sci Scu sec sec sed sel sel sem seq set sha she sho sid sie sil sim sin sit sky slo sno sod sol sol sol sol son sou spa spa spe spe spe spe sph spi spo squ sta sta sta sta ste ste ste Sti sto str str sub sub sub sul sup sup sup sup sur sur syl syn sys tal Tay tel ten ter tex the the the the Tho thr tid tim Tit too Tor tra tra Tra tra Tra tri Tri tru tub tur two Typ ult ult unc uni uni uni upl ura uti val var vec vel ver Ver vie vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>