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Hydrus âbmâr (#) Fr.: Hydre mâle The Male Water Snake. A minor constellation with three main stars, one of the 15 → circumpolar constellations in the southern hemisphere. It first appeared in Johann Bayer's Uranometria of 1603. It is often confused with → Hydra, the large constellation further north. It is also referred to as "male Hydra" or "little Hydra." Abbreviation: Hyi; genitive: Hydri. From L., from Gk. hydros "water serpent." Âbmâr "water snake," from âb "water" (Mid.Pers. âb "water;" O. Pers. ap- "water;" Av. ap- "water;" cf. Skt. áp- "water;" Hitt. happa- "water;" PIE āp-, ab- "water, river;" cf. Gk. Apidanos, proper noun, a river in Thessalia; L. amnis "stream, river" (from *abnis); O.Ir. ab "river," O.Prus. ape "stream," Lith. upé "stream;" Latv. upe "brook") + mâr "snake, serpent" (Mid.Pers. mâr "snake;" Av. mairya- "snake, serpent"). |
hygro- nam- (#) Fr.: hygro- A combining form meaning "wet, moist, moisture," used in the formation of compound words: → hygrogram; → hygrograph; → hygrometer . Hygro-, from Gk, combining form of hygros "wet, moist." Nam "humidity, moisture" + -negâšt, → -gram. The first component nam, from Mid.Pers. nam, namb "moisture;" Av. napta- "moist," nabās-câ- "cloud," nabah- "sky;" cf. Skt. nábhas- "moisture, cloud, mist;" Gk. nephos "cloud, mass of clouds," nephele "cloud;" L. nebula "mist," nimbus "rainstorm, rain cloud;" O.H.G. nebul; Ger. Nebel "fog;" O.E. nifol "dark;" from PIE *nebh- "cloud, vapor, fog, moist, sky." |
hygrogram namnegâšt (#) Fr.: hygrogramme The graphical record made by a → hygrograph. |
hygrograph namnegâš (#) Fr.: hygrographe An instrument that records the hygrometer's measure of water vapor. |
hygrometer namsanj (#) Fr.: hygromètre An instrument that measures the relative humidity of the air. |
hylotrope mâdegard Fr.: hylotrope A member of a class of equations of state used in some models concerned with the evolution of a hypothetical supermassive star. The supermassive star is assumed to consist of a → convective core, which obeys a → polytropic law, and an envelope, which contains most of the whole mass, and follows the hylotropic → equation of state. This equation is expressed by P = A ρ^{4/3}M^{α}, where A is a constant, ρ the density, M the mass, and α an index. First introduced by Mitchell C. Begelman (2010, MNRAS 402, 673). From → hylotropic, on the model of → polytrope. |
hylotropic mâdegard Fr.: hylotropique Physical chemistry: Describing a substance that is capable of undergoing a change in phase (as from a liquid to a gas), with no change in chemical composition. If the substance is hylotropic over a limited range of pressure and temperatures, it is a pure chemical substance. If it is hylotropic over all pressure and temperatures except the most extreme ones, it is a → chemical element. See also → hylotrope. First suggested by Wilhelm Ostwald (1904, in Annalen der Naturphilosophie 3, 355), from Gk. hylo-, combining form of hyle "matter; wood," because of the dependence on the composition, + → -tropic. |
hylotropy mâdegardi Fr.: hylotropie Physical chemistry: The fact or condition of being → hylotropic. → hylotropic; → -tropy. |
hyper- 1) abar- (#); 2) hiper- (#) Fr.: hyper- A prefix appearing in loanwords from Greek meaning: From Gk. hyper, preposition and adverb, "over, beyond, overmuch, above;" cognate with L. super- and Pers. abar-, as below. 1) Mid.Pers. abar; O.Pers.
upariy "above; over, upon, according to;" Av. upairi "above, over,"
upairi.zəma- "located above the earth;" cf. Gk. hyper- "over, above;"
L. super-; O.H.G. ubir "over;" PIE base *uper "over." |
hyperbola hozluli (#) Fr.: hyperbole A two-branched open curve, a type of conic section, defined as the intersection between a right circular conical surface and a plane which cuts through both halves of the cone. From Gk. hyperbole "excess, exaggeration" literally "a throwing beyond," from hyperballein "to throw over or beyond," from → hyper- "beyond" + bol-, nom. stem of ballein "to throw." Hozluli, loanword from Ar. |
hyperbolic hozluli (#) Fr.: hyperbolique Of or pertaining to a → hyperbola. |
hyperbolic cosine kosinus-e hozluli Fr.: cosinus hyperbolique A function, denoted cosh x, defined for all real values of x, by the relation: cosh x = (1/2) (e^{x} + e^{-x}). → hyperbolic; → cosine. |
hyperbolic function karyâ-ye hozluli Fr.: fonction hyperbolique Any of the six functions sinh, cosh, tanh, coth, csch, and sech that are related to the → hyperbola in the same way the → trigonometric functions relate to the → circle. Many of the formulae satisfied by the hyperbolic functions are similar to corresponding formulae for the trigonometric functions, except for + and - signs. For example: cosh^{2}x - sinh^{2}x = 1. See also: → hyperbolic cosine, → hyperbolic sine. Hyperbolic functions were first introduced by the Swiss mathematician Johann Heinrich Lambert (1728-1777). → hyperbolic; → function. |
hyperbolic orbit madâr-e hozluli (#) Fr.: orbite hyperbolique An orbit that is an open curve whose ends get wider apart at any rate between that of an ellipse and a straight line. Some comets' orbits become hyperbolic through the gravitational influence of a planet the comet passes near. → hyperbolic; → orbit. |
hyperbolic sine sinus-e hozluli Fr.: sinus hyperbolique A function, denoted cosh x, defined for all real values of x, by the relation: cosh x = (1/2) (e^{x} - e^{-x}). → hyperbolic; → sine. |
hyperbolic space fazâ-ye hozluli (#) Fr.: espace hyperbolique A three-dimensional space whose geometry resembles that of a saddle-shaped surface and is said to have negative curvature. → hyperbolic; → space. |
hyperboloid hozlulivâr (#) Fr.: hyperboloïde A surface or body obtained by rotating a hyperbola about its axis of symmetry. Hyperboloid, from hyperbol(a) + → -oid a suffix meaning "resembling, like." Hozlulivâr, from hozluli, → hyperbola, + -vâr a suffix of similarity. |
hyperfine abar-nâzok Fr.: hyperfine Extremely fine or thin, especially of a → spectral line split into two or more very thin components. → hyperfine structure; → hyperfine transition. → hyper-, → fine structure. |
hyperfine structure sâxtâr-e abar-nâzok (#) Fr.: structure hyperfine In spectroscopy, the → splitting of a spectral line into a number of very thin components. It results from a small perturbation in the energy levels of atoms or molecules due to the magnetic dipole-dipole interaction arising from the interaction of the nuclear → magnetic moment with the → spin of the electron. It can be observed only at high spectral dispersion. → fine structure. |
hyperfine transition gozareš-e abar-nâzok Fr.: transition hyperfine An → atomic transition involving a → hyperfine structure. → hyperfine; → transition. |
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