# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 1342
 curvature of space-time   خمیدگی ِ فضا-زمان   xamidegi-ye fazâ-zamân (#)Fr.: courbure de l'espace-temps   According to → general relativity, → space-time is curved by the presence of → matter. The curvature is described in terms of → Riemann's geometry. In → cosmological models three types of curvature are considered: positive (spherical, → closed Universe), zero (Euclidean, → flat Universe), and negative (hyperbolic, → open Universe). See also → curvature constant.→ curvature; → space-time. curve   خم   xam (#)Fr.: courbe   A line that deviates from straightness in a smooth, continuous fashion. A line representing a variable on a graph.From L. curvus "crooked, curved, bent;" cf. Av. skarəna- "round," Gk. kirkos, krikos "a ring;" PIE base *sker- "to turn, bend."Xam, variant kamân "arc," Mid.Pers. kamân, probably from PIE *kamb- "to bend, crook," cf. Breton kamm "curved, bent." curve fitting   سز ِ خم، سزکرد ِ ~   saz-e xam, sazkard-e ~Fr.: ajustement de courbe   Construction of mathematical functions whose graphs are curves that "best" approximate a given collection of data points.→ curve; → fitting. curve of growth   خم ِ رویش   xam-e ruyešFr.: courbe de croissance   A plot showing how the → equivalent width of an → absorption line, or the radiance of an → emission line, increases as a → function of the → number of → atoms that produce the line.→ curve; → growth. curved   خمیده   xamidé (#)Fr.: courbé   Not straight.Adj. from → curve. curvilinear   خم‌خط   xam-xattFr.: curviligne   Consisting of, represented by, or bound by curved lines. → rectilinear.From → curve + → linear. cusp   تیزه   tizé (#)Fr.: cuspide   1) General: Pointed end. A point of transition. → polar cusp. 2) Either point of a → crescent moon. 3) A steep power-law representing the number density of stars in the central region of a galaxy. Cusps are characteristic of low-mass ellipticals. They are thought to result from the gravitational attraction of a central → supermassive black hole. 4) A peaked concentration of dark matter in the center of galaxies, as predicted by the → cold dark matter (CDM) model of galaxy formation. See also → cusp problem. 5) Math: A tooth-like meeting of two branches of a curve, with sudden change of direction.L. cuspis "point, spear, pointed end."Tizé, noun from tiz "sharp, pointed," from Mid.Pers. tēz, tēž, tigr "sharp," O.Pers. tigra- "pointed," Av. taēža-, tighra- "pointed," Skt. taējas- "the sharp edge (of a knife), piercing (flame)", from tij- "to be sharp, to pierce," Gk. stizein "to prick, puncture," stigma "mark made by a pointed instrument," L. instigare "to goad," P.Gmc. *stik- "to pierce, prick, be sharp," O.H.G. stehhan, Ger. stechen "to prick," O.E. stician "to pierce, stab," E. stick "to pierce;" PIE *st(e)ig- "to stick; pointed". cusp problem   پراسه‌ی ِ تیزه   parâse-ye tizéFr.: problème des cuspides   A problem encountered by the → cold dark matter (CDM) model of galaxy formation. The numerical simulations with CDM predict a large concentration of dark matter in the center of galaxies, with a peaked density distribution, in contrast to the real, observed galaxies. See also: → angular momentum catastrophe; → missing dwarfs.→ cusp; → problem. cut   بریدن   boridan (#)Fr.: couper   To penetrate or divide something, as with a sharp-edged instrument.M.E. cutten, kytten, kitten; O.E. *cyttan, cognate with O.Swed. kotta "to cut;" O.N. kuti "little knife," or from O.Fr. couteau "knife."Boridan "to cut off;" Mid.Pers. brin-, britan, brinitan "to cut off," brin "cut, delimitation, determined;" Av. (pairi-) brī- "to shave, shear;" cf. Skt. bhrī- "to hurt, injure," bhrinanti "they hurt." cutoff   بره   boréFr.: coupure   1) A designated limit beyond which the passage of something must be stopped. 2) A device that cuts off a transmission of photons.→ cut; → off.Boré, from bor- present stem of boridan "to → cut" + noun suffix -é. cutoff filter   پالایه‌ی ِ بره   pâlâye-ye boréFr.: filtre à coupure   Filter rejecting all light with wavelengths on one side of the cutoff wavelength.→ cutoff; → filter. cutoff voltage   ولتاژ ِ بره   voltâž-e boréFr.: tension de coupure   The electrode voltage which reduces the value of a dependent variable, e.g. anode current, to a specified low value.→ cutoff; → voltage. cutoff wavelength   موج-طول ِ بره   mowj-tul-e boréFr.: longueur d'onde de coupure   Wavelength at which the transmittance of a filter, or the detectivity of a detector, has fallen to one-half its peak value.→ cutoff; → wavelength. cyanide   سیانور   siyânur (#)Fr.: cyanure   A chemical compound that contains the → cyano radical, -CN. Most cyanides are highly toxic.→ cyano-; → -ide. cyano radical   رادیکال ِ سیانو   râdikâl-e siyânoFr.: radical cyano   A diatomic chemical radical composed of carbon and nitrogen atoms. The triple bonds of C to H leave one electron available, which makes the CN radical very reactive. Organic molecules with the -CN group are potential sources of → prebiotic amino acids. Same as the → CN molecule. The CN radical was first identified by Gay-Lussac, who in 1815 published an extensive study of the derivatives of prussic acid (→ hydrogen cyanide). He showed that the cyano radical remained intact throughout a series of chemical transformations. Also called cyanogen radical.→ cyano-; → radical. cyano-   سیانو-   siyâno- (#)Fr.: cyano-   1) A combining form meaning "blue, dark blue," used in the formation of compound words. Also cyan- before a vowel. 2) A combining form representing → cyanide in the formation of chemical compounds.From Gk. kyanos "dark blue, lapis lazuli," because of its presence in the Prussian blue, Fe7(CN)18, a dye which was first accidentally made around 1706, by heating substances containing iron and carbon and nitrogen. cyanogen   سیانوژن   siyânožen (#)Fr.: cyanogène   1) A colorless, very poisonous, flammable gas with a smell of bitter almonds. Chemical formula: C2N2. It was discovered by Louis Joseph Gay-Lussac (1778-1850) in 1848. 2) A univalent radical, CN, found in simple and complex cyanide compounds. CN exists in → interstellar medium and is one of the main molecules detected in → comets. It has energy levels at 113 and 227 GHz (2.6 and 1.3 mm wavelength) above the ground level.→ cyano- + → -gen. cyanogen band   باند ِ سیانوژن   bând-e siyânožen (#)Fr.: bande de cyanogène   An → absorption band of molecular origin characterizing the spectra of → late-type stars (G0 and later, e.g. → S star). → Cyanogen absorption is an important → luminosity criterion for → low-mass stars, and is more pronounced in → giant stars than in → dwarf stars of the same → spectral type.→ cyanogen; → band. cycle   چرخ، چرخه   carx (#), carxé (#)Fr.: cycle   1) A sequence of changes that are repeated regularly, such as revolution, rotation, vibration, oscillation, wave motion. 2) One complete set of changes in the value of a → periodic function during one period. 3) A period of time at the end of which an event or sequence of events are repeated. → carbon cycle, → Carnot cycle, → CNO cycle, → hydrologic cycle, → Metonic cycle, → Milankovich cycle, → solar activity cycle, → solar cycle, → solar magnetic cycle, → sunspot cycle, → epicycle, → recycle. 4) In → graph theory, a closed → path with at least one → edge.From L.L. cyclus, from Gk. kyklos "circle, wheel," from PIE base *kw(e)-kwl-o- "wheel, circle," from *kwel- "to turn, move around, sojourn, dwell," (cf. Av. caxra- "wheel," caraiti "he moves, approaches;" Mod.Pers. carx "wheel;" Skt. cakra- "wheel, circle; cycle," carati "he moves, wanders;" Gk. polos "axis of a sphere," polein "move around;" L. colere "to dwell in, to cultivate, move around," colonus "farmer, settler;" O.E. hweol "wheel;" Rus. koleso "awheel").Carx "every thing performing a circulatory motion; a wheel; a cart," Mid.Pers. chr "wheel," Parthian cxr "wheel," Ossetic, Khotanese calx "wheel," Av. caxra- "wheel," cognate with Gk. kyklos "circle, wheel," as above. Carxé from carx + nuance suffix -é. cyclic   چرخه‌ای   carxe-yi (#)Fr.: cyclique   Of, pertaining to, or constituting a cycle or cycles.→ cycle; → -ic.