An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1259
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 ruyeš

Fr.: 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.

xamidé (#)

Fr.: courbé   

Not straight.

Adj. from → curve.


Fr.: curviligne   

Consisting of, represented by, or bound by curved lines. → rectilinear.

From → curve + → linear.

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 tizé

Fr.: 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.

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."


Fr.: 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 .

cutoff filter
  پالایه‌ی ِ بره   
pâlâye-ye boré

Fr.: filtre à coupure   

Filter rejecting all light with wavelengths on one side of the cutoff wavelength.

cutoff; → filter.

cutoff voltage
  ولتاژ ِ بره   
voltâž-e boré

Fr.: 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 boré

Fr.: 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.

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 siyâno

Fr.: 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.

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.

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.

  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 .

carxe-yi (#)

Fr.: cyclique   

Of, pertaining to, or constituting a cycle or cycles.

cycle; → -ic.

cyclic coordinate
  همارای ِ نادیده‌انگاشته   
hamârâ-ye nâdidé engâshté

Fr.: coordonnée ignorée   

Same as → ignorable coordinate.

cyclic; → coordinate.

cyclic group
  گروه ِ چرخه‌ای   
goruh-e carxe-yi

Fr.: groupe cyclic   

A group in which each element can be expressed as a power of any other element.

cyclic; → group.

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