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: 1251
coefficient
  همگر   
hamgar (#)

Fr.: coefficient   

1) Math.: A number or letter placed before an algebraic expression to indicate that the expression is to be multiplied by that factor, e.g. in the expression 2 x3, 2 is the coefficient of x3. In general, any factor of a product is called the coefficient of the product of the remaining factors.
2) Physics: Factor which measures some specified property of a given substance, and is constant for that substance under given conditions, such as the coefficient of friction. → factor.

Hamgar, from ham- "together," → com- + -gar agent suffix, from kar-, kardan "to do, to make," Mid.Pers. kardan, O.Pers./Av. kar- "to do, make, build," Av. kərənaoiti "makes," cf. Skt. kr- "to do, to make," krnoti "makes," karma "act, deed;" PIE base kwer- "to do, to make."

coefficient of viscosity
  همگر ِ وشکسانی   
hamgar-e vošksâni

Fr.: coefficient de viscosité   

A quantity that indicates a property of fluids and is defined by the ratio of shearing → stress to the rate of change of shearing → strain. It is also simply called viscosity. The coefficient of viscosity is expressed by: μ = (F/A) / (dv/dy), where F is the force required to maintain a steady velocity difference dv between any two parallel layers of the fluid, A is the area of the layers, and dv/dy is the → velocity gradient between two points separated by a small distance measured at right angles to the direction of flow. The unit of viscosity is that of force times distance divided by area times velocity. Thus, in the cgs system, the unit is 1 dyne.cm/cm2.(cm/s), which reduces to 1 dyne.s/cm2. This unit is called 1 → poise.

viscosity; → coefficient.

coelostat
  آسمان داشتار   
âsmândâštâr

Fr.: coelestat   

A flat mirror with a clock-drive mounted in such a way that it moves from east to west to compensate for the apparent rotation of the Earth in order that the image of a particular area of sky remains fixed in the focal plane. See also → siderostat and → heliostat.

Coelostat, from L. coelo-, for caeli-, combination form of coelum "sky" + -stat prefix denoting something that stabilizes, keeps, fixes, from -stata, from Gk. -states "one that causes to stand," or statos "standing," from *sta- "to stand."

Âsmândâštâr, from âsmân, → sky, + dâštâr "holder, maintainer," from dâštan "to hold, maintain; to have; to possess," Mid.Pers. dâštan, O.Pers./Av. root dar- "to hold, keep back, maitain, keep in mind," Skt. dhr-, dharma- "law," Gk. thronos "elevated seat, throne," L. firmus "firm, stable," Lith. daryti "to make," PIE *dher- "to hold, support."

coeval
  هم‌سن   
hamsenn (#)

Fr.: du même âge, contemporain   

Of the same age.

From L. co-, → com-, + aevum "age," → aeon.

Hamsenn "equally old," from ham-, → com-, + sennage.

cofactor
  همکروند   
hamkarvand

Fr.: cofacteur   

A number associated with an → element of a → determinant. If A is a square matrix [aij], the cofactor of the element aij is equal to (-1)i+j times the determinant of the matrix obtained by deleting the i-th row and j-th column of A.

co-; → factor.

cognition
  شناختار   
šenâxtâr (#)

Fr.: connaissance, cognition   

1) The mental process of knowing, including → awareness, → perception, → reasoning, and judgment.
2) The product of such a process; something thus known, perceived, etc. (Dictionary.com).

M.E. cognicioun; L. cognitionem (nominative cognitio, from cognitus p.p. of cognoscere, from → co- + gnoscere, noscere "to learn;" cognate with Pers. šenâs, šenâxt, as below.

Šenâxtâr, verbal noun of šenâxtan "to know, recognize," dânestan "to know;" O.Pers./Av. xšnā- "to know, learn, come to know, recognize;" cf. Skt. jñā- "to recognize, know," jānāti "he knows;" Gk. gignoskein "to know, think, judge;" L. gnoscere, noscere "to come to know" (Fr. connaître; Sp. conocer); O.E. cnawan; E. know; Rus. znat "to know;" PIE base *gno- "to know."

cognitive
  شناختاری   
šenâxtâri (#)

Fr.: cognitif   

1) Of or pertaining to the act or process of knowing, perceiving, remembering, etc.; of or relating to → cognition.
2) Of or pertaining to the mental processes of perception, memory, judgment, and reasoning, as contrasted with emotional and volitional processes (Dictionary.com).

cognition; → -ive.

cohere
  همدوسیدن   
hamdusidan (#)

Fr.: adhérer, être cohérent   

1) To stick together; be united; hold fast, as parts of the same mass.
2) Physics (of two or more similar substances) to be united within a body by the action of molecular forces (→ cohesion).

From L. cohaerere "to cleave together," from → com- "together," + haerere "to stick."

Hamdusidan, from ham- "together," → com-, + dusidan (Dehxodâ) "to stick, to adhere," → adhere.

coherence
  همدوسی   
hamdusi (#)

Fr.: cohérence   

The property of two or more electromagnetic waves when they are in fixed phase relationship over time. If the crests and troughs of the waves meet at the same time and place they are said to be in phase.

cohere + -ence, → -ance.

coherence area
  پهنه‌ی ِ همدوسی   
pahne-ye hamdusi

Fr.: zone de cohérence   

Of an electromagnetic wave, the area of a surface perpendicular to the direction of propagation, over which the electromagnetic wave maintains a specified degree of coherence.

coherence; → area.

coherence length
  درازا‌ی ِ همدوسی   
derâzâ-ye hamdusi

Fr.: longueur de cohérence   

The distance over which an electromagnetic wave train maintains a specified degree of coherence.

coherence; → length.

coherence time
  زمان ِ همدوسی   
zamân hamdusi

Fr.: temps de cohérence   

The time over which a propagating electromagnetic wave may be considered coherent. The coherence time of an interferometer is the interval during which the fringe phase remains stable.

coherence; → time.

coherent
  همدوس   
hamdus (#)

Fr.: cohérent   

Two or more wave sources are said to be coherent sources if the phase difference between a pair of points, one in each source, remains constant.

Coherent, adj., → coherence.

coherent light
  نور ِ همدوس   
nur-e hamdus (#)

Fr.: lumière cohérente   

Light waves that have the same wavelength and possess a fixed phase relationship, as in a laser.

coherent; → light.

coherent optics
  نوریک ِ همدوس   
nurik-e hamdus

Fr.: optique cohérente   

A branch of optics that uses coherent radiation to produce holographic three-dimensional images of objects.

coherent; → optics.

coherent scattering
  پراکنش ِ همدوس   
parâkaneš-e hamdus

Fr.: diffusion cohérente   

A scattering process in which the scattered radiation bears the same frequency and phase as the incident radiation.

coherent; → scattering.

coherent source
  خن ِ همدوس   
xan-e hamdus

Fr.: source cohérente   

One of two light beams derived from the same source in → interference experiments. It is impossible to obtain interference from two separate sources because their → wavefronts do not have a constant → phase difference. In → Young's experiment, → Fresnel's biprism, → Fresnel's mirrors, and → Lloyd's mirror the two sources always have a point-to-point correspondence of phase, since they are both derived from the same source.

coherent; → source.

cohesion
  همدوسش   
hamduseš (#)

Fr.: cohésion   

Holding together.
Physics: The attraction between the molecules of a solid or liquid that holds the parts of the substance together.

From L. cohæsus, p.p. of cohærere "to stick together," → coherence.

Hamduseš, verbal noun from hamdusidan "to cohere," → coherence.

cohesive
  همدوسنده، همدوسشی   
hamdusandé, hamduseši

Fr.: cohésif   

1) Of or pertaining to the molecular force → cohesion.
2) Characterized by or causing → cohesion.

Adjective from → cohere.

cohesive energy
  کاروژ ِ همدوسش   
kâruž-e hamduseš

Fr.: énergie de cohésion   

The energy associated with the chemical bonding of atoms in a solid.

cohesive; → energy.

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