An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 481
harunegâri (#)

Fr.: holographie   

A technique for making three-dimensional images by recording → interference patterns from a split → laser beam on a medium such as photographic film. One of the → coherent beams irradiates the object, the second beam illuminates a recording medium. The two beams produce an interference pattern, called → hologram, on the film. The hologram contains information on both → phase and → amplitude of the object. However, this information is in a coded form, and the image must be reconstructed. When the object is removed and the hologram is illuminated by the laser from the original direction, a 3-dimensional image of the object appears where the object was originally, as if it were not removed. The visible object seems so real that the observer can detect → parallax by changing the position of one's head.

From → holo- "whole" + → -graphy. By using the term holography, Dennis Gabor (1900-1979), the Hungarian-British electrical engineer and inventor, wanted to stress that the technique records complete information about a wave, both about its amplitude and its phase, in contrast to the usual photography in which only the distribution of the amplitude is recorded.

holonomic system
  راژمان ِ هروداتیک   
râžmân-e harudâtik

Fr.: système holonomique   

A material system in which the → constraints can be expressed in the form of an equation relating the coordinates.

From Gk. → holo- "whole" + -nomic, related to nomos "law, managing, governing, custom," → -nomy; → system.

bozorgdâšt (#)

Fr.: hommage   

1) Respect or reverence paid or rendered.
2) Something done or given in acknowledgment or consideration of the worth of another (

M.E. (h)omage, from O.Fr. homage "allegiance or respect for one's feudal lord," from homme "man," → human, + -age.

Bozordgâšt, literally "considered to be great," from bozorg "large, magnificent, great," → magnify, + dâšt, dâštan "to maintain, consider, possess, keep in mind, hold, have," → property.

ham- (#)

Fr.: homo-   

A combining form meaning "same" used in the formation of compound words. Also, especially before a vowel, hom-.

Homo-, from Gk. homos "one and the same," also "belonging to two or more jointly," from PIE *somos; cf. Pers. ham-, as below; Lith. similis "like," Goth. sama "the same," samana "together."

Ham- "together, with; same, equally, even," Mid.Pers. ham-, like L. com- and Gk. syn- with neither of which it is cognate. O.Pers./Av. ham-, Skt. sam-; also O.Pers./Av. hama- "one and the same," Skt. sama-, Gk. homos-; originally identical with PIE numeral *sam- "one," from *som-. The Av. ham- appears in various forms: han- (before gutturals, palatals, dentals) and also hem-, hen-.

homocentric spheres
  سپهرهای ِ هم‌مرکز   
sepehrhâ-ye ham-markaz

Fr.: sphères homocentriques   

Concentric → spheres of Eudoxus.

homo-; → center; → -ic; → sphere.


Fr.: homodyne   

Of, or pertaining to the process of combining two waves, such as → electromagnetic waves, of the same → frequency. See also: → heterodyne.

Homodyne, from → homo- + -dyne, from Gk. dynamicsdynamics.

hamgeni (#)

Fr.: homogénéité   

State or quality of having a uniform appearance or composition, being homogeneous

homogeneous + → -ity.

hamgen (#)

Fr.: homogène   

1) Of uniform composition or having a common property throughout.
2) Math.: Of the same kind so as to be commensurable. Of the same degree or dimension. → anisotropic homogeneous cosmological model, → homogeneous fluid, → homogeneous linear differential equation, → homogeneous Universe, → homogeneous turbulence, → inhomogeneous, → nonhomogeneous, → nonhomogeneous linear differential equation.

Homogeneous, from M.L. homogeneus, from Gk. homogenes "of the same kind," from homos "same," → homo-, + genos "race, kind," gonos "birth, offspring," from PIE base *gen-/*gon-/*gn- "to produce, beget, be born," cf. Av. zan- "to bear, give birth to a child, be born," infinitive zazāite, zāta- "born," zana- "race" (in sruuô.zana- "belonging to the race of the horned ones"), O.Pers. zana- "tribe" (in paru-zana- "consisting of many tribes"), Skt. janati "begets, bears," jana- "creature, human being, race, tribe, people;" L. genus "race, stock, kind," gignere "to beget."

Hamgen "of the same kind, like each other; friend, partner," from ham-, → homo-, + gen "kind," O.Pers./Av. zana- "race; tribe," cognate with L. genus, as above). Alternatively, gen may be a variant of Mid./Mod.Pers. gôn/gun "kind, type; manner; color, skin color," from Av. gaona- "hair, hair color, color."

homogeneous fluid
  شارّه‌ی ِ همگن   
šârre-ye hamgen (#)

Fr.: fluide homogène   

A fluid with uniform properties throughout, but meteorologists sometimes designate as homogeneous a fluid with constant density.

homogeneous, → fluid.

homogeneous linear differential equation
  هموگش ِ دگرسانه‌ای ِ خطی همگن   
hamugeš-e degarsâne-yi-ye xatti hamgen

Fr.: équation différentielle linéaire homogène   

A → linear differential equation if the right-hand member is zero, Q(x) = 0, on interval I.

homogeneous; → linear; → differential; → equation.

homogeneous turbulence
  آشوبناکی ِ همگن   
âšubnâki-ye hamgen (#)

Fr.: turbulence homogène   

Turbulence in which spatial derivatives of all mean turbulent quantities are negligible.

homogeneous, → turbulence.

homogeneous Universe
  گیتی ِ همگن   
giti-ye hamgen (#)

Fr.: Univers homogène   

A model Universe which is homogeneous and → isotropic on large scales. It is modeled by a → Robertson-Walker cosmology. A homogeneous Universe is filled with a constant density and negligible pressure. Any small spatial region is characteristic for the whole Universe.

homogeneous; → Universe.


Fr.: homomorphisme   

A → mapping between two mathematical → objects that preserves the object structure. A general → morphism.

homo-; → morphism.

homonuclear molecule
  مولکول ِ هم‌هسته   
molekul-e ham-hasté

Fr.: molécule homonucléaire   

A molecule that is composed of only one type of → chemical element, e.g. the → molecular hydrogen and → ozone.

homo-; → nuclear; → molecule.


Fr.: homopause   

The altitude at which → molecular diffusion replaces → eddy diffusion as the dominant vertical transport mechanism. Light gases separate out from heavier ones above this altitude. The flux of hydrogen through the homopause is limited by diffusion.

homo-; + pause "break, cessation, stop," from M.Fr. pause, from L. pausa "a halt, stop, cessation," from Gk. pausis "stopping, ceasing," from pauein "to stop, to cause to cease."

Hamgen, → homogeneous, + marz "frontier, border, boundary," → frontier. frontier.


Fr.: homosphère   

Based on chemical composition, the Earth atmosphere is divided into two broad layers: the homosphere and the → heterosphere. The homosphere extends from the surface of the Earth up to the height of about 90 km. It is characterized by an almost homogeneous composition of nitrogen (78%), oxygen (21%), argon (10%), carbon dioxide as well as traces of constituents like dust particles, → aerosols and cloud droplets.

homo-; → shere.

Homunculus Nebula
  میغ ِ آدمک   
miq-e âdamak

Fr.: nébuleuse de l'Homoncule   

A nebula of gas and dust (about 17" x 12" in size), which surrounds the massive star Eta Carinae and lies about 7500 light-years away. The surrounding material was ejected by the massive star in 1843 during its violent eruption, and is now expanding at about 500 km/sec.

Homunculus, "a diminutive human being; little man" (since the nebula resembled a small human to early observers), from L. homin-, homun-, homo "eartly being," humus "the earth" (cf. Pers. zamin "earth, ground," Mid.Pers. zamig "earth;" Av. zam- "the earth;" Skt. ksam; Gk. khthôn, khamai "on the ground;" PIE root *dh(e)ghom "earth") + → -ula, -ule; → nebula.

Miq, → nebula; âdamak "little man."


Fr.: crochet   

1) A curved or bent piece of metal or other hard material for catching, holding, or hanging something.
2) Something curved or bent like a hook.

M.E. hoke, O.E. hoc "hook, angle;" cf. M.Du. hoek, Du. haak, Ger. Haken "hook."

Qollab "a hook, a hooked device," probably ultimately from Proto-Ir. gart- "to turn;" cf. Pers. gard-, gardidan, gaštan "to turn, to wind;" cognate with dialectal qellidan "to roll."

Hooke's law
  قانون ِ هوک   
qânun-e Hooke (#)

Fr.: loi de Hooke   

The law stating that if a body is deformed the → strain produced is directly proportional to the applied → stress. If the elastic limit is not exceeded, the material returns to its original shape and size on the removal of the stress. Hooke's law forms the basis of the theory of → elasticity.
More specifically, within certain limits, the force required to stretch an elastic object such as a metal spring is directly proportional to the extension of the spring. It is commonly written: F = -kx, where F is the force, x is the length of extension/compression and k is a constant of proportionality known as the spring constant.

Named after Robert Hooke (1635-1703), British scientist who described the relationship in 1676; → law.


Fr.: 1) sautiller, sauter; 2) sautillement, saut   

1) To move by a quick springy leap or in a series of leaps. (Of a person) Move by jumping on one foot. (Of a bird or other animal) move by jumping with two or all feet at once.
2) An act of hopping; short leap.

M.E. hoppen; O.E. hoppian; cognate with Ger. hopfen, O.N. hoppa.

Kopidan, from kop; cf. (Bašâgardi) kup, (Lârestâni) komp, (Bardesiri) gopak, (Sistâni) job, (Kermâni) pok, pokidan "jump, leap."

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