An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1062

Fr.: préon   

In → particle physics, any of postulated "point-like" particles from which are composed → quarks and → leptons. In other words, preon models assume there is a more fundamental kind of particle than those so far known. Different preon models consider different numbers and different natures of the preons.

Coined by Jogesh Pati and Abdus Salam in 1974, from → pre- + → -on.

preplanetary nebula (PPN)
  پیش-میغ ِ سیاره‌ای   
piš-miq-e sayyâre-yi

Fr.: pré-nebuleuse planétaire   

A short-lived transition object between the → asymptotic giant branch (AGB) and → planetary nebula phases. See also → post-asymptotic giant branch star (post-AGB).

pre-; → planetary; → nebula. The more commonly used term, → protoplanetary nebula, is a misnomer and must be avoided. Indeed → protoplanetary is widely used to refer to disks around → pre-main sequence stars. Since the term → protoplanet is used to denote planets undergoing formation, the use of the term "protoplanetary nebula" to mean a completely different kind of object is an unfortunate choice (Sahai et al. 2005, ApJ 620, 948).


Fr.: préposition   

A word used with a noun or pronoun to mark its relation with another word.

From L. praepositionem "a putting before," from praepositus, p.p. of praeponere "put before," from prae "before," → pre-, + ponere "put, set, place," → position.

Pišhel, from piš-, "before," → pre-, + hel-, helidan, heštan "to place, put," → leap.


Fr.: pré-publication   

An advance printing, usually of an article in a periodical.

pre-; → print.


Fr.: préscientifique   

Relating to a stage or time prior to the rise of modern science and to the application of the → scientific method.

pre-; → scientific.

  پیش‌وشتن، پیش‌ویسیدن   
pišveštan, pišvisidan

Fr.: prescrire   

1) To lay down, in writing or otherwise, as a rule or a course of action to be followed; appoint, ordain, or enjoin.
2) Medicine: To designate or order the use of a medicine, remedy, treatment, etc. (

pre-; + scribe, → describe.

  پیش‌وشت، پیش‌ویس   
pišvešt, pišvis

Fr.: prescription, ordonnance   

1) An act of prescribing.
2) A direction, usually written, by the physician to the pharmacist for the preparation and use of a medicine or remedy. The medicine prescribed (

Verbal noun of → prescribe; → -tion.

  پیش‌وشتی، پیش‌ویسنده   
pišvešti, pišvisandé

Fr.: normatif   

1) That prescribes; giving directions or injunctions.
2) Depending on or arising from effective legal prescription, as a right or title established by a long unchallenged tenure (

prescribe; → -ive.


Fr.: présence   

The state or fact of being present.

Noun from → present.

  ۱) پیشاست، باشنده؛ ۲، ۳) پیشاست، کنون، کنونی   
1) pišâst, bâšandé; 2, 3) pišâst, konun, konuni

Fr.: présent   

1) Being, existing, or occurring at this time or now.
2) At this time; at hand; immediate.
3) Grammar: Noting an action or state occurring at the moment of speaking.

M.E., from O.Fr. present, from L. præsentem (nominative præsens) "present, immediate," from pr.p. of præesse "to be before, to be at hand," from præ- "before," → pre-, + esse "to be;" cf. Pers. ast "is," hastan, astan "to be;" O.P. ah- "to be," astiy "is;" Av. ah- "to be," astī "is;" Skt. as- "to be," ásti "is;" Gk. esti "is;" PIE base es- "to be."

Pišâst, on the model of L. præesse, as above, from piš, → pre-, + epenthetic -â- + ast "is," variants hast, hi, has (Qâyen), isâ (Rašt), a (Aftar), heye (Kurd.); Av./O.Pers. ah- "to be," Proto-Ir. *Hah- "to be," → existence.
Bâšandé agent noun from budan "to be;" → condition.
Konuni "presently," from konun, aknun "now, present," from *hak-nun, from *hak-, cf. Av. hakat- "at once, immediately" + nū- "now" (Mid/Mod.Pers. nun "now, at present"); Av. nūrəm "now;" O.Pers. nūram "now;" Skt. nú- "now, just, but," nūnám "now, at present, indeed;" Gk. nun "now;" L. nu- "now" (in nu-dis "the day after tomorrow"); Goth. nu "now;" O.E. nu; E. now; PIE base *nu- "now."

present day
emruz (#)

Fr.: époque actuelle, aujourd'hui   

Same as → present epoch, → today, → current cosmological epoch.

present; → day.

present epoch
  زیمه‌ی ِ کنونی   
zime-ye konuni

Fr.: époque actuelle   

Same as → present day, → today, → current cosmological epoch.

present; → epoch.

present participle
  پارگرته‌ی ِ کنون   
pârgerte-ye konun

Fr.: participe présent   

A → participle that indicates an ongoing action or state in the present.

present; → participle.

present-day mass function (PDMF)
  کریای ِ جرم ِ کنونی، ~ ~ امروزی   
karyâ-ye jerm-e konuni, ~ ~ emruzi

Fr.: fonction de masse actuelle   

The present number of stars on the → main sequence per unit logarithmic mass interval per square parsec. The PDMF is the basis for deriving the → initial mass function (IMF). This mass function is not corrected for stellar evolution nor losses through stellar deaths.

present; → day; → mass; → function.


Fr.: présider   

To occupy the place of authority or control, as in an assembly or meeting; act as president or chairperson (

pre-; → reside.


Fr.: président   

1) The highest executive officer of a modern republic, as the Chief Executive of the United States (often initial capital letter).
2) An officer appointed or elected to preside over an organized body of persons (

preside; → -ent.

Farneštgâr, from farnešt, present stem of farneštidan, → preside, + agent noun suffix -gâr, → -or, on the model of âmuzgâr "teacher."


Fr.: pré-solaire   

Of or relating to an epoch earlier than the formation of the Sun.

pre-; → solar.

presolar grain
  دانه‌ی ِ پیش-خورشیدی   
dâne-ye piš-xoršidi

Fr.: grain pré-solaire   

A → refractory → nanoparticle embedded in → meteorites and → interplanetary dust particles whose → isotopic ratios suggest formation earlier than the Solar System.

presolar; → grain.

Press-Schechter formalism
  دیسه‌گرایی ِ پرس-ششتر   
disegerâyi-ye Press-Schechter

Fr.: formalisme de Press-Schechter   

A mathematical analysis, based on → self-similarity, used to predict the → mass function of spherically collapsing → dark matter halos. The formalism assumes that the fraction of mass in halos more massive than M is related to the fraction of the volume in which the smoothed initial density field is above some threshold δcρ, where ρ is the average density of the Universe, with the volume encompassing a mass larger than M. A variety of smoothing → window functions and thresholds have been argued, but the most common is a top-hat window in real space and δc≅ 1.69. The Press-Schechter formalism provides a relatively good fit to the results of numerical simulations in cold dark matter theories.

First described by William H. Press and Paul Schechter's paper (1974, ApJ 187, 425); → formalism.

fešâr (#)

Fr.: pression   

The force per unit area.

M.E., from O.Fr. pressure, from L. pressura "action of pressing," from pressus, p.p. of premere "to press, compress."

Fešâr "squeezing, constriction, compression," verb fešordan, fešârdan "to press, squeeze;" phonetic variants Lori xošâr, Aftari xešâr, Qazvini, Qomi xošâl; cf. Khotanese ssarr- "to exhilarate;" loaned in Arm. ôšarak, in Ar. afšaraj "juice."

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