An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 763

Fr.: déflexion   

The act or state of deflecting or the state of being deflected. Amount of deviation.
Electronics: In a cathode-ray tube, the bending, by a magnetic field, of the beam of electrons after the focused beam leaves the electron gun.

Verbal noun of → deflect.

deflection angle
  زاویه‌ی ِ واچفت   
zâviye-ye vâcaft

Fr.: angle de déflexion   

1) The angle by which a light ray is curved by the gravitational field of a massive body. Einstein's general relativity predicts that a light ray which tangentially grazes the surface of the Sun is deflected by 1''.7. This result was confirmed in 1919 when the apparent angular shift of stars close to the limb of the Sun was measured during a total solar eclipse.
2) In a cathode-ray tube, the angle through which the beam is bent, vertically, horizontally, or diagonally.

deflection; → angle.

deflection of light
  واچفت ِ نور   
vâcaft-e nur

Fr.: déflexion de la lumière   

The bending of a light ray under the gravitational effect of a massive body. → deflection angle.

deflection; → light.


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1) No longer in effect or use; not operating or functioning.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."

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