An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 755

Fr.: défocaliser   

To cause to deviate from accurate focus.

vâ- + → focus.

  ۱) وادیسیدن؛ ۲) وادیساندن   
1) vâdisidan; 2) vâdisândan

Fr.: 1) se déformer; 2) déformer   

1) To undergo → deformation.
2) To change the form or shape of. → deformable, → deformed, → deformation.

From O.Fr. déformer, from L. deformare "to disfigure," from → de- + → form.

Vâdisidan, vâdisândan infinitive from vâdis, from vâ-, → de-, + dis, → form.


Fr.: déformable   

Capable of being → deformed. → deformable mirror

deform + → -able.

deformable mirror
  آینه‌ی ِ وادیسیدنی   
âyene-ye vâdisidani

Fr.: miroir déformable   

A very thin mirror whose shape can be changed by the force applied by many small pistons behind the mirror. Such a mirror is used in the → adaptive optics technique to correct the → wavefront affected by the → atmospheric turbulence. See also → tip-tilt mirror.

deformable; → mirror.

  وادیس، وادیسش، وادیسانش   
vâdis, vâdiseš, vâdisâneš

Fr.: déformation   

Altering in the size or shape of a body. See also → deformable.

Verbal noun of → deform.


Fr.: déformé   

Having the → form → changed.

Past participle of → deform.


Fr.: défunt   

1) No longer in effect or use; not operating or functioning.
2) No longer in existence; dead; extinct.

M.E., from O.Fr. defunct or directly from L defunctus "dead," literally "off-duty," from p.p. of defungi "to discharge, finish," from → de- "off, completely" + fungi "perform or discharge duty," from PIE root *bheug- "to enjoy" (cognates: Latin fructus).

Nâkâr, "disabled" (Dehxodâ), leterally "not working," from negation prefix nâ-, → un-, + kâr, kardan, → work

defunct comet
  دمباله‌دار ِ ناکار   
dombâledâr-e nâkâr

Fr.: comète défunte   

A comet that has lost its ability to emit dust and gas and no longer displays the classic cometary features of a nebulous coma and a tail, or a destroyed comet. Comet Pigott The asteroid (944) Hidalgo is considered by some to be a defunct comet because of its unusual orbit. Another case is the asteroid Phaethon.

defunct; → comet.


Fr.: défuzzification, concrétisation   

The process of producing a quantifiable result in a → fuzzy logic system, given → fuzzy sets and corresponding → membership functions. Defuzzification is the last step in a fuzzy logic system. After → fuzzy inferencing, the overall result is a → fuzzy value. This result should be defuzzified to obtain a final → crisp value.

Verbal noun of → defuzzify; → -tion.


Fr.: défuzzifier   

To transform a → fuzzy set to a → crisp set in a → fuzzy logic system.

de-; → fuzzy; → -fy.

vâgeni (#)

Fr.: dégénérescence   

1) General: Degenerate state or character. Reverting to an earlier, simpler, state.
2) Math.: Limiting case in which a class of object changes its nature so as to belong to another, usually simpler, class.
3) Physics: In quatum mechanics, the condition in which two or more different → wave functions of a system correspond to the same energy. In the case of atomic energy levels, the degeneracy can be removed, for example, by applying an electric field to the atom.
State or charcater of → degenerate matter.

From degener(ate), → degenerate, + -acy suffix of nouns of quality and state.

Vâgeni, from vâgen, → degenerate, + noun suffix -i.

degeneracy pressure
  فشار ِ واگنی   
fešâr-e vâgeni (#)

Fr.: pression de dégénérescence   

Pressure in a degenerate electron or neutron gas. → degenerate matter.

degeneracy; → pressure.

vâgen (#)

Fr.: dégénéré   

Characterized by or associated with → degeneracy.

L. degeneratus, p.p. of degenerare "depart from one's kind, fall from ancestral quality," from → de- + gener-, stem of genus "race, stock, kind," gignere "to beget," cf. with Gk. 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."

Vâgen, from vâ-, → de-, + gen "kind," (as in hamgen "of the same kind, like each other; friend, partner," from ham- "together," → com- + 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."

degenerate dwarf
  کوتوله‌ی ِ واگن   
kutule-ye vâgen

Fr.: naine dégénérée   

Same as → white dwarf.

degenerate; → dwarf.

degenerate matter
  ماده‌ی ِ واگن   
mâdde-ye vâgen (#)

Fr.: matière dégénérée   

Highly compressed matter in which the normal atomic structure has broken down and which, because of quantum-mechanical effects, exerts a pressure that is independent of temperature. Bodies with masses less than → Chandrasekhar's limit (1.4 solar masses) are supported by electron → degeneracy pressure and have densities of about 106 kg/m3. In collapsed stars of mass above 1.4 solar masses, gravity will overwhelm electron degeneracy and further collapse ensues. Electrons combine with protons to form neutrons, so producing a → neutron star. Because neutrons, like electrons, are → fermions and therefore subject to the → Pauli exclusion principle, at high enough densities, about 1014 kg/m3, neutron degeneracy pressure prevents further collapse of the star. For masses larger than 2-3 solar masses, even neutron degeneracy cannot prevent further collapse, and a → black hole is formed.

degenerate; → matter.


Fr.: dégrader   

1) To lower in dignity or estimation; bring into contempt.
2) To lower in character or quality; debase.
3) Chemistry: Of a compound, especially an organic hydrocarbon, to break down (

de-; → grade.

darajé (#)

Fr.: degré   

1) Subdivision of an interval in a scale of measurement.
2) Geometry: Measure of angle, the 360th part of a circle.
3) Math.: Rank of an equation or expression as determined by the sum of the exponents of the variables.

From O.Fr. degré, from V.L. *degradus "a step," from L.L. degredare, from L. → de- "down" + gradus "step."

Darajé, from Ar. darajat "step, ladder."

degree of coherence
  درجه‌ی ِ همدوسی   
dareje-ye hamdusi

Fr.: degré de cohérence   

The extent of → coherence of an → electromagnetic wave, as indicated by a → dimensionless number. Since interference takes place when waves are → coherent, using a → Young's experiment, the degree of coherence is measured from the → fringe  → visibility, V. It is defined as the ratio V = (Imax - Imin) / (Imax + Imin), where Imax is the intensity at a maximum of the → interference pattern, and Imin is the intensity at a minimum of the interference pattern. The electromagnetic wave is considered to be highly coherent when the degree of coherence is about 1, incoherent for nearly zero values, and partially coherent for values between 0 and 1.

degree; → coherence.

degree of freedom
  درجه‌ی ِ آزادی   
daraje-ye âzâdi (#)

Fr.: degré de liberté   

Of a → mechanical system, the number of → independent variables needed to describe its configuration.

degree; → freedom.

degree of ionization
  درجه‌ی ِ یونش   
daraje-ye yoneš (#)

Fr.: degré d'ionisation   

The number of electrons a neutral atom has lost in an ionizing physical process (radiation, shock, collision). In spectroscopy, the degree of ionization is indicated by a Roman numeral following the symbol for the element. A neutral atom is indicated by the Roman numeral I, a singly ionized atom, one which has lost one electron, is indicated by II, and so on. Thus O VI indicates an oxygen atom which has lost five electrons.

degree; → ionization.

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