An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 678
Dirichlet condition
  بوتار ِ دیریکله   
butâr-e Dirichlet

Fr.: condition de Dirichlet   

One of the following conditions for a → Fourier series to converge:
1) The function f(x) is defined and single valued, except possibly at a finite number of points in the interval -π, +π.
2) f(x) has a period of 2π.
3) f(x) and f'(x) are → piecewise continuous functions on -π, +π.
Then, the Fourier series converges to:
(a) f(x) if x is a point of continuity.
(b) (f(x + 0) + f(x - 0))/2, if x is a point of discontinuity.

Named after Peter Gustav Lejeune Dirichlet (1805-1859), German mathematician who made valuable contributions to → number theory, → analysis, and → mechanics; → condition.

dirt
  چرک   
cerk (#)

Fr.: saleté   

A substance, such as mud or dust, that soils someone or something (OxfordDictionaries.com)

Metathesis of M.E. drit, drytt "mud, dirt, dung," from O.N. drit, cognate with O.E. dritan.

Cerk "dirt, filth."

dirty
  چرکین   
cerkin (#)

Fr.: sal   

Covered or marked with an unclean substance. → dirty ice, → dirty iceball model.

dirt + suffix -y.

dirty ice
  یخ ِ چرکین   
yax-e cerkin

Fr.: glace sale   

Interstellar ice grains with graphite, silicates, or other chemical compounds adsorbed on their surfaces.

dirty; → ice.

dirty iceball model
  مدل ِ گلوله‌ی ِ یخ   
model-e golule-ye yax

Fr.: modèle de la boule de glace sale   

A model for a → cometary nucleus proposed by Fred Whipple (1950-51), according to which the nucleus is a solid body (a few kilometers across) made up of various → ices (→ frozen water, → methane, → ammonia, → carbon dioxide, and → hydrogen cyanide) in which → dust is embedded. Dust particles are liberated when the ices vaporize as the → comet approaches the → Sun, and they get blown away by → solar radiation pressure, often forming impressive, gently curved → dust tails.

dirty; → ice; → ball; → model.

dis-
     
vâ- (#)

Fr.: dis-   

A prefix meaning "lack of, not" (e.g. dishonest); "do the opposite of" (e.g. disallow); "apart, away" (e.g. discard); before f, dif-; before some consonants (b, d, l, m, n, r, s, v, and sometimes g and j) di-.

From O.Fr. des-, from L. dis- "apart," from PIE *dis- "apart, asunder" (cf. O.E. te-, O.S. ti-, O.H.G. ze-, Ger. zer-). The PIE root is a secondary form of *dwis- and is thus related to L. → bis "twice."

Vâ- prefix denoting "separation; repetition; open; reversal, opposition; off; away," variant of bâz-, from Mid.Pers. abâz-, apâc-; O.Pers. apa- [pref.] "away, from;" Av. apa- [pref.] "away, from," apaš [adv.] "toward the back;" cf. Skt. ápāñc "situated behind."

disallocate
  واتسکیدن   
vâteskidan

Fr.: desallouer   

Computers: To cancel the assignment of a particular resource to a user.

dis- + → allocate.

disallocation
  واتسک   
vâtesk

Fr.: desallouation   

The act of disallocating or the state of being disallocated.

dis- + → allocate.

disapproval
  واسند   
vâsand

Fr.: déapprobation   

The act or state of disapproving; a condemnatory feeling, look, or utterance.

dis-; → approval.

disapprove
  واسندیدن   
vâsandidan

Fr.: désapprover   

To withhold approval from; decline to sanction.

dis-; → approve.

discharge
  وابار   
vâbâr

Fr.: décharge   

The removal or transference of an electric charge, as by the conversion of chemical energy to electrical energy.
The sudden and momentary equalization of a difference of potential, as between two terminals.

From M.E. deschargen, from O.Fr. deschargier "unload," from L.L. discarricare, from → dis- "do the opposite of" + carricare "to load a cart," from carrus "cart."

Vâbâr, from vâ- reversal prefix, → de- + bârcharge.

disciplinarity
  هاوشانیگی، هاوشان‌مندی   
hâvešânigi, hâvešânmandi

Fr.: disciplinarité   

The quality or state of being → disciplinary.

disciplinary; → -ity.

disciplinary
  هاوشانی، هاوشان‌مند   
hâvešâni, hâvešânmand

Fr.: disciplinaire   

Of, for, or constituting a → discipline. See also → interdisciplinary, → multidisciplinary, and → transdisciplinary.

discipline; → -ary.

discipline
  هاوشان   
hâvešân

Fr.: discipline   

1) A branch of learning or instruction.
2) A system of rules for behavior, methods of practice, etc.

M.E., from M.Fr. discipline, descepline, from L. disciplina literally "teaching, instruction," from discipulus "pupil, student, follower," from dis- + cipere, combining form of capere "to take," → concept, + -ulus, → -ule.

Hâvešân, from hâveš "disciple, pupil," Mid.Pers. hâvišt "disciple, pupil;" Av. hāvišta- "disciple, pupil," + -ân a suffix denoting "group, order, system."

discontinuity
  ناپیوستگی   
nâpeyvastegi (#)

Fr.: discontinuité   

A break in sequence or continuity of anything. → Balmer discontinuity
Math.: A point at which a function is not continuous.
Geology: A surface separating rock layers of differing properties or compositions.

M.L. discontinuitas, from discontinuus, from → dis- + continuus, → continuous.

Nâpeyvastegi, noun from nâpeyvasté "discontinuous," from nâ- "non, un-," → a-, + peyvasté, → continuous.

discover
  پدواریدن، کشف کردن   
padvâridan, kašf kardan

Fr.: découvrir   

To find (something previously unseen or unknown) after study or search.

M.E. discoverir, descovrir, from O.Fr. descovrir "uncover, unveil, reveal," from L.L. discooperire, from L. → dis- "opposite of" + cooperire "to cover up," → cover.

Padvâridan "to uncover," infinitive from padvâr, from prefix pad- "against, contrary, opposite to," variants pat-, pâd-, → anti-, + vâr- "to cover;" cf. Av. vār- "to cover;" Mid.Pers. (with prefix *uz-) uzvâr- "to interprete, uncover, grasp," Pers. hozvâr(eš) "interpretation;" Khotanese (+ *ui-) gvir- "to be revealed;" Choresmian (+ *apa-) bw'rg- "to uncover;" Pers. barg "cover, clothes;" šalvâr "trousers" (Cheung, 2007).

discovery
  پدوار، پدوارش، کشف   
padvâr, padvâreš, kašf

Fr.: découverte   

The act or an instance of discovering. Something discovered.

Verbal noun of → discover.

discrepancy
  ناهم‌خوانی   
nâhamxâni (#)

Fr.: écart, désaccord   

Divergence or disagreement, as between facts, claims, or calculations.

From L. discrepantia, from discrepantem, pr.p. of discrepare "sound differently, differ," from → dis- "apart, off" + crepare "to rattle, crack."

Nâhamxâni, from nâ- "non, un-," → a-, + hamxâni "siniging together," from ham- "together," → com-, + xâni, from xân stem of xândan "to sing; to read; to call," Mid.Pers. xwân- "to resound; to call," Av. xvan- "to sound," Proto-Iranian *huan- "to call;" cf. Skt. svan-, sváranti "to sound, make a sound, sing;" L. sonus "sound," sonare "to sound;" O.E. swinn "music, song," PIE base *suen- "to sound" (Cheung 2007).

discrete
  گسسته، جدا   
gosasté, jodâ (#)

Fr.: discret   

Apart or detached from others; separate; distinct. Composed of distinct or discontinuous elements.

From O.Fr. discret, from L. discretus "separated, distinct," from p.p. of discernere "to distinguish," from → dis- "off, away" + cernere "distinguish, separate, sift," → crisis.

Gosasté "broken, broken off," p.p. of gosastan "to break, split," Mid.Pers. wisistan "to break, split," Av. saed- "to split," asista- "unsplit, unharmed," Skt. chid- "to split, break, cut off," Gk. skhizein "to split," L. scindere "to split;" PIE stem *skei- "to split, cut."
Jodâ "separate, distinct," Mid.Pers. jutâk (yutâk), jut (yut).

discrete absorption component (DAC)
  همنه‌ی ِ درشمی ِ گسسته   
hamne-ye daršami-ye gosasté

Fr.: composante d'absorption discrète   

The rapid, systematic changes in the absorption parts of the → P Cygni profiles of the ultraviolet → resonance lines (Si IV, C IV, and N V) observed in a majority of massive → hot stars. DACs are typically seen to accelerate to the → blue wing of the profile over a few days, becoming narrower as they approach the → terminal velocity.

discrete; → absorption; → component.

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