An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1076
photovisual magnitude
  بُرز ِ شیدچشمی   
borz-e šidcašmi

Fr.: magnitude photovisuelle   

Magnitude defined for the combination of a photographic plate and a yellow filter, approximating the spectral sensitivity of the eye.

photo- + → visual; → magnitude.

photovoltaic detector
  آشکارگر ِ شید-ولتایی   
âškârgar-e šidvoltâyi

Fr.: détecteur photovoltaïque   

A detector usually constituted by a p-n junction. Upon irradiation, the electron-hole pairs which are created, are immediately separated by the strong electric field across the junction, and a current is generated, which is proportional to the number of incident photons per second.

photo- + → voltaic; → detector.


Fr.: locution, expression   

A sequence of two or more words arranged in a grammatical construction and acting as a unit in a → sentence.

From L.L. phrasis "diction," from Gk. phrasis "speech, way of speaking, enunciation," from phrazein "to express, tell," from phrazesthai "to consider."

Vatpâr, literally "part of speech," from vat-, "to speak, say;" cf. (Kurd.) wittin "to speak, say," → letter, + pâr "piece, part, portion," → partial.

fiziki (#)

Fr.: physique   

Pertaining to the physical sciences, especially physics.

physics + → -al.

physical adsorption
  برشم ِ فیزیکی   
baršam-e fiziki

Fr.: adsorption physique   

Same as → physisorption.

physical; → adsorption.

physical chemistry
  شیمی ِ فیزیکی   
šimi-ye fiziki (#)

Fr.: chimie physique   

The branch of chemistry dealing with the relations between the physical properties of substances and their chemical composition and transformations.

physical; → chemistry.

physical condition
  بوتار ِ فیزیکی   
butâr-e fiziki

Fr.: condition physique   

The state of a → physical system regarding its temperature, density, pressure, etc. at a given time.

physical; → condition.

physical constant
  پایای ِ فیزیکی   
pâyâ-ye fiziki (#)

Fr.: constante physique   

A fundamental → physical quantity that is generally believed to be both universal in nature and constant in time.

physical; → constant.

physical dimension
  وامون ِ فیزیکی   
vâmun-e fiziki

Fr.: dimension physique   

Any of basic physical quantities, such as mass, length, time, electric charge, and temperature in terms of which all other kinds of quantity can be expressed.

physical; → dimension.

physical law
  قانون ِ فیزیکی   
qânun-e fiziki (#)

Fr.: loi physique   

A theoretical principle which is deduced from particular observational facts regarding the behavior of matter. Physical laws are expressed by a general statement that a particular → physical phenomenon always occurs if certain → conditions are present.

physical; → law.

physical libration
  هلازان ِ فیزیکی، رخگرد ِ ~   
halâzân-e fiziki, roxgard-e ~

Fr.: libration physique   

A real periodic variation in the rotation rate of a celestial object, as distinct from a → geometrical libration. In particular, slight oscillations in the → Moon's rotation caused by the → gravitational attraction of the Earth on the → equatorial bulge of the Moon's near side. The Moon's physical libration is about 0.03° in longitude and about 0.04° in latitude.

physical; → libration.

physical optics
  نوریک ِ فیزیکی   
nurik-e fiziki

Fr.: optique physique   

The branch of optics concerned with the wave properties of light, → diffraction, → polarization, and other phenomena for which the ray approximation of → geometric optics is not valid. Also called → wave optics.

physical; → optics.

physical parameter
  پارامون ِ فیزیکی   
pârâmun-e fiziki

Fr.: paramètre physique   

Any of a set of physical properties whose values determine the characteristics or behavior of a system; for example, → mass, → size, → temperature, → luminosity, etc.

physical; → parameter.

physical phenomenon
  پدیده‌ی ِ فیزیکی   
padide-ye fiziki (#)

Fr.: phénomène physique   

A natural → phenomenon that can be explained by → physical laws.

physical; → phenomenon.

physical quantity
  چندای ِ فیزیکی   
candâ-ye fiziki (#)

Fr.: quantité physique   

A physical → property that can be measured and/or calculated.

physical; → quantity.

physical system
  راژمان ِ فیزیکی   
râžmân-e fiziki

Fr.: système physique   

A set of physical components chosen to study their relations.

physical; → system.

fizikdân (#)

Fr.: physicien   

A specialist in → physics.

From physic, → physics, + → -ist.

Fizikdân, from fizik, → physics, + -dân "knower," present stem of dânestan "to know," → science.

fizik (#)

Fr.: physique   

The science that deals with matter and energy and their interactions.

M.E. fisyk(e), phisik(e), from O.Fr. fisique, from L. physica (fem. sing.) "study of nature," from Gk. physike episteme "knowledge of nature," from fem. of physikos "pertaining to nature," from physis "nature," from phyein "to bring forth, produce, make to grow," Gk. phy- "to become;" L. fui "I was," futurus "that is to be, future;" Ger. present first and second person sing. bin, bist; E. to be; O.Ir. bi'u "I am;" Lith. bu'ti "to be;" Rus. byt' "to be."

Loan from Fr. physique, as above.


Fr.: physisorption   

A kind of → adsorption in which the forces involved are → intermolecular  → van der Waals forces. Same as → physical adsorption. See also → chemisorption.

Physi-, from → physical; → sorption.

pi number
  عدد ِ پی   
adad-e pi (π)

Fr.: nombre pi (π)   

Symbol, π, for the ratio of the circumference of a circle to its diameter in Euclidean geometry; a fundamental mathematical constant, equal to 3.14159... π is an → irrational number (Lambert, 1761) and also a → transcendental number (von Lindemann, 1882). The most accurate determination of π prior to the Scientific Revolution belongs to the Iranian mathematician Jamshid Kashani, who gave 16 correct decimal places in A.D. 1424. With the advent of → calculus and more recently the invention of powerful computers, the decimal representation of π has now been computed to more than 1012 digits.

The π notation, representing the first letter of the Gk. word περιμετρον → perimeter, was first used by the British mathematician William Jones (1675-1749) in 1706. Its use was generalized after its adoption by the Swiss mathematician Leonard Euler (1707-1783) in 1737; → number.

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