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
latent heat
  گرمای ِ نهان   
garmâ-ye nahân (#)

Fr.: chaleur latente   

The amount of → thermal energy that is absorbed or released by a unit amount of a substance in the process of a phase change under conditions of constant pressure and temperature.

latent; → heat.

lateral
  کناری، پهلویی، بری   
kenâri, pahluyi, bari

Fr.: latéral   

Of or relating to the side; situated at, proceeding from, or directed to a side (Dictionary.com).

M.E., from O.Fr. latéral and directly from L. lateralis "belonging to the side," from latus "the side, flank; lateral surface."

Kenâri, relating to kenâr, → side.

latitude
  وَرونا   
varunâ

Fr.: latitude   

The angle between a perpendicular at a location, and the → equatorial plane of the Earth. → longitude. See also:
astronomical latitude, → celestial latitude, → circle of latitude, → colatitude, → ecliptic latitude, → Galactic latitude, → geocentric latitude, → geodetic latitude, → geographic latitude, → high latitudes, → horse latitudes, → middle latitudes, → spherical latitude, → supergalactic latitude.

L. latitudo "breadth, width, size," from latus "wide," from PIE base *stela- "to spread" (cf. O.C.S. steljo "to spread out," Arm. lain "broad").

Varunâ, from var "breadth, side, breast," variant bar, Tabari vari "width," Mid.Pers. var "breast," Av. varah- "breast" (Sk. vara- "width, breadth") + -u a suffix forming adjectives; Av. vouru- "wide;" + -nâ a suffix of dimension.

lattice
  جاره   
jâré

Fr.: réseau   

1) A regular geometric arrangement of points in a plane or in space.
2) → Crystal lattice.
3) A structure in a nuclear reactor containing nuclear fuel and other materials arranged in a regular geometrical pattern.
4) Math.: A partially ordered set in which each two-element subset has both a greatest lower bound and a least upper bound.

From O.Fr. latiz "lattice," from late "lath, board, plank, batten" (Fr. latte); cf. O.H.G. latta "lath."

Jâré, from jarra "net; snare," Afghan jâli "reticulated garment," Tabari jarazin "grilled apparatus used in a watercourse to gather thatch and trash;" cf. Skt. jāla- "net, snare, lattice."

lattice energy
  کاروژ ِ جاره   
kâruž-e jâré

Fr.: énergie réticulaire   

The energy required to separate an ion from a → crystal to an infinite distance. In other words, the energy released when one → mole of a crystal is formed from gaseous ions.

lattice; → energy.

latus rectum
  تار ِ راست   
târ-e râst

Fr.: latus rectum   

The chord through a focus and perpendicular to then major axis of a conic section.

L. latus "side;" rectum "straight," → right.

Târ "thread, warp, string" (related to tur "net, fishing net, snare," tâl "thread" (Borujerdi dialect), tân "thread, warp of a web," from tanidan, tan- "to spin, twist, weave;" Mid.Pers. tanitan; Av. tan- to stretch, extend;" cf. Skt. tan- to stretch, extend;" tanoti "stretches," tántra- "warp; essence, main point;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" Lith. tiñklas "net, fishing net, snare," Latv. tikls "net;" PIE base *ten- "to stretch."

lava
  گدازه   
godâzé (#)

Fr.: lave   

Molten → magma released from a volcanic vent or fissure.

Lava, from It. lava "torrent, stream," from L. lavare "to wash;" PIE base *lou- "to wash;" cf. Persian Lori, Kurdi, Malâyeri laf "flood," variants Tabari , [Mo'in, Dehxodâ] lur, lây "flood;" Gk. louein "to wash."

Godâzé noun from godâxtan "to melt," from 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."

law
  قانون، ارته   
qânun (#), arté (#)

Fr.: loi   

1) A rule of conduct or procedure established by custom, agreement, or authority.
2) A code of principles based on morality, conscience, or nature.
3) Physics: A statement of a scientific fact or phenomenon that is invariable under given conditions; e.g. → Newton's law of gravitation, → second law of thermodynamics.
4) Math.: A general principle deduced from particular facts expressed by the statement that a particular phenomenon always occurs if certain conditions are present.

M.E., O.E. lagu, from O.N. *lagu, variant of lag "that which is laid down;" cf. Ger. liegen, E. lay, lie; PIE *legh- "To lie, lay;" compare with Hittite laggari "falls, lies," Gk. lekhesthai "to lie down," L. lectus "bed," O.Ir. lige "bed, tomb," Tokharian lake, leke "bed."

Qânun, from Ar., ultimately from Gk. kanon "rule."
Arté, from O.Pers. arta- "law, justice;" Av. arəta-, ərəta- "law, order," variant aša- "truth, cosmic order," aipi-ərəta- "firmly assigned," from root ar- "to fix;" cf. Skt. rtá- "truth, world order; oath;" Ossetci ard "oath;" Gk. arthon "limb, articulation," artus "a joint;" L. artus "a joint;" PIE base *ar- "to join, to fit together."

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.

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