An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 446
First Point of Aries
  نقطه‌ی ِ آغاز ِ برّه   
noqte-ye âqâz-e barré (#)

Fr.: premier point de Bélier   

One of the two points on the celestial sphere where the ecliptic and the celestial equator crossed one another at → vernal equinox several thousands years ago.

first; → point; → Aries.

First Point of Libra
  نقطه‌ی ِ آغاز ِ ترازو   
noqte-ye âqâz-e tarâzu (#)

Fr.: permier point de Balance   

One of the two points on the celestial sphere where the ecliptic and the celestial equator crossed one another at → autumnal equinox several thousands years ago. Because of → precession, this equinoctial point no longer lies in Libra but in neighboring Virgo.

first quarter
  چارک ِ نخست   
cârak-e naxost

Fr.: premier quartier   

A → lunar phase that occurs in the middle of the interval between the → new Moon and the → full Moon, when half of the Moon's disk is illuminated. At first quarter, the Moon is situated at 90° east of the Sun.

first; → quarter.

first star
  نخستین ستاره   
naxostin setâré

Fr.: première étoile   

A member of the → Population III → massive stars that formed some 500 Myr after the → Big Bang. First stars had a simple chemical composition consisting only of H, He, and traces of 7Li and were very short-lived. They are the most likely sources of → reionization of the Universe, which put an end to the → Cosmic Dark Age.

first; → star.

first-order differential equation
  هموگش ِ دگرسانه‌ای ِ رایه‌ی ِ نخست   
hamugeš-e degarsâne-yi-ye râye-ye naxost

Fr.: équation différentielle du premier ordre   

A → differential equation containing only the first → derivative. For example, dy/dx = 3x and 2y(dy/dx) + 3x = 5.

first; → order; → differential; → equation.

first-order logic (FOL)
  گوییک ِ فراسنی ِ رایه‌ی ِ نخست، ~ فراسنهای ِ ~ ~   
guyik-e farâsani-ye râye-ye naxost, ~ farâsanhâ-ye ~ ~

Fr.: logique des prédicats du premier ordre   

A system of → formal logic that is an extension of → propositional logic. It is also known as → first-order predicate calculus and → predicate logic. FOL eliminates deficiencies of propositional logic by: representing → objects (their properties, relations and statements about them), introducing → variables, and introducing → quantifiers.

first; → order; → predicate; → logic.

first-order partial derivative
  واخنه‌ی ِ پاری ِ رایه‌ی ِ نخست   
vâxane-ye pâri-ye râye-ye naxost

Fr.: dérivée partielle du premier degré   

For a → function with several → variables, the derivative, done only once, with respect to one of the variables. For example ∂u/∂x for u = u(x,y).

first; → order; → partial; → derivative.

first-order predicate calculus
  افماریک ِ فراسنی ِ رایه‌ی ِ نخست   
afmârik-e farâsani-ye râye-ye naxost

Fr.: cacul des prédicats du premier ordre   

Same as → first-order logic.

first; → order; → predicate; → calculus.

first-order spectrum
  بیناب ِ رایه‌ی ِ نخست   
binâb-e râye-ye naxost

Fr.: spectre du premier ordre   

An optical spectrum, produced by a diffraction grating, in which the difference in path length of light from adjacent slits is one wavelength.

first; → order; → spectrum.

mâhi (#)

Fr.: poisson   

A limbless cold-blooded vertebrate animal with gills and fins living wholly in water (

M.E. fis(c)h, fyssh, O.E. fisc; cognate with Du. vis, Ger. Fisch, O.Norse fiskr, Goth. fisks; akin to L. piscis; PIE root *pisk- "a fish."

Mâhi "fish," from Mid.Pers. mâhik; Av. masya-; cf. Skt. matsya-, Pali maccha-.

  شکافت‌پذیر، شکافتنی   
šekâftpazir (#), šekâftani (#)

Fr.: fissile   

Any material that is capable of undergoing → nuclear fission by → thermal neutrons. The three primary fissile materials are uranium-233, uranium-235, and plutonium-239. Although sometimes used as a synonym for → fissionable material, this term has acquired a more restricted meaning.

From L. fissilis, from fiss(us), + -illis a suffix of adjectives expressing capability, susceptibility, liability, aptitude, etc.

Šekâftani, from šekâft, → fission + -i a suffix expressing capability, aptitude, etc.

fissile isotope
  ایزوتوپ ِ شکافت‌پذیر   
izotop-e šektpazir

Fr.: isotope fissile   

An isotope that is capable of undergoing nuclear fission after capturing either fast neutron or thermal neutron. Typical fissionable isotopes: 238U, 240Pu, but also 235U, 233U, 239Pu, 241Pu

fissile; → isotope .

šekâft (#)

Fr.: fission   

1) The act or process of splitting or breaking into parts.
2) Splitting of the nucleus of an atom into two or more fragments of comparable size, usually as the result of the impact of a neutron on the nucleus. Same as → nuclear fission.

Fission, from L. fissionem "a breaking up, cleaving," from root of findere "to split."

Šekâft, stem of šekâftan "to split, break, tear," akin to kaftan, kâftan "to split; to dig," Parthian Mid.Pers. q'f- "to split;" Sogdian "to split;" Chorasmian kf- "to split, be split;" Proto-Iranian *kap-, *kaf- "to split."

fission products
  فر‌آورده‌های ِ شکافت   
farâvardehâ-ye šekâft (#)

Fr.: produits de fission   

Nuclides generated by the fission of higher mass elements or by subsequent radioactive decay of nuclides directly generated by fission.

fission; → product.

šekâftpazir (#)

Fr.: fissile   

The material that can be fissioned by fast neutrons, such as uranium-238. Commonly used as a synonym for → fissile material.

From → fission + → -able.

  ۱) سز کردن؛ ۲) سز   
1) saz kardan; 2) saz

Fr.: 1) ajuster; 2) ajustement   

1) (v.) To pass a mathematical line or curve through data points.
2) (n.) The act of fitting.

From M.E. fitten; akin to M.Du. vitten "to befit."

Saz, from sazidan "to suit, fit, be worthy," sazâ "suitable, agreeing with, congruous, deserving of," Mid.Pers. sacitan/sazidan "to fit," sazešn "fitness," sazâg "fitting, worth;" Av. 1sak- "to understand or know a thing; to mark;" cf. Skt. śak- "to be able, powerful" śakta- "able, competent," śakti- "ability, power;" alternatively from Av. 2sak- "to go by, pass, pass away; to be up or over (of time)."

  سزکرد، سز   
saz-kard, saz

Fr.: ajustement   

The process or instance of adapting a mathematical curve to data points.

Verbal form of → fit.

fitting error
  ایرنگ ِ سزکرد، ~ سز   
irang-e saz-kard, ~ saz

Fr.: erreur d'ajustement   

The discrepancy between the mathematical curve and data points. → fit.

fitting; → error.

panj (#)

Fr.: cinq   

A cardinal number whose symbol is 5, V, or ۵.

Five, from O.E. fif, from P.Gmc. *fimfe (cf. O.S. fif, O.H.G. funf), from PIE *penkwe "five;" cognate with Pers. panj, as below.

Panj, from Mid.Pers. panj; Av. panca; cf. Skt. páñca; Gk. pente; L. quinque; E. five, as above.

five-color system
  راژمان ِ پنج‌رنگه   
râžmân-e panj-rangé

Fr.: système à cinq couleurs   

A photometric system which uses five filters, from ultraviolet to the red part of the visual spectrum: U, B, V, R and I.

five; → color; → system.

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