An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 687
ether drift
  دلک ِ اتر   
delek-e eter

Fr.: dérive de l'éther   

1) The hypothetical motion of the supposed → ether relative to the Earth. The → Michelson-Morley experiment found no ether drift. An analogy is given by a boat drifting in a fast-flowing river due to the river's current. With the same power, the speed would be slower when sailing across the stream. Moreover, in order to reach directly opposite the starting point, the boat would have to be headed somewhat upstream. See also the → ether drag.
2) The motion of the Earth relative to the → rest frame defined by the → cosmic microwave background radiation.

ether; → drift.

qowm- (#)

Fr.: ethno-   

A combining form meaning "race, culture, people."

From Gk. ethnos "people, nation, class, tribe."

Qowm- loan from Ar. qaum "people, tribe, family."


Fr.: ethnologie   

The study of the beliefs, interpretations, and practices of specific cultures regarding celestial objects or phenomena. Ethnoastronomy uses the tools and methodologies of → ethnology in the study of astronomical conceptions.

ethno-; → astronomy.


Fr.: ethnologie   

The study of specific cultures (ethnic groups) in their different aspects (anthropological, social, cultural, etc.) to establish similarities and disparities between them.

ethno-; → logy.

etil (#)

Fr.: éthyl   

A chemical group, C2H5, produced by removing a hydrogen atom from → ethane. For example, ethyl chloride is C2H5Cl

From Ger. Ethyl, from eth-, from → ether, + -yl a suffixed used in the names of radicals.

ethyl alcohol
  اتیل الکل   
etil alkol (#)

Fr.: éthyl alcool   

Same as → ethanol.

ethyl; → alcohol.

riše-šenâsi (#)

Fr.: étymologie   

The study of the origins and history of the form and meaning of → words.

M.E., from L. etymologia, from Gk. etymologia, from etymon "true sense" (neuter of etymos) + logos, → -logy.

Riše-šenâsi, from rišé "root" (dialectal Tabari rexa; Kurd. regez, riše), from Mid.Pers. rêšak "root," maybe ultimately related to PIE *u(e)rad-, although the Skt. offshoot is absent (Gk. rhiza "root;" L. radix, radius "staff;" O.H.G. wurz "plant, herb;" Ger. Wurz; O.E. rot; E. root) + -šenâsi, → -logy.

hu- (#)

Fr.: eu-   

A prefix meaning "good, well; true, genuine" (eupepsia; eukaryote); opposed to → dys-.

L. from Gk. eu "well," combining form of eus "good" (hu-gies "healthy"); cf. Mid.Pers. hu-; Av. hu- "good;" PIE base *su- "good," see below.

Mid.Pers. hu- "good, well" (hu-boy "sweet-smelling," hu-cihr "beautiful," hu-mânih "good-mindedness"); O.Pers. hu- "good, well" (ukāra- "having good people"); Av. hu-, hū- "well, good, beautiful" (hu-kərp- "well-shapen," hūxta- "well spoken," hu-manah- "good-minded"); Skt. su- "good" (svasti "well-being, good luck," sumánas- "good-minded," sūktá- "well spoken"); Gallic su-; O.S. su-; Welsh hy-; PIE base *su-, as above.

Oqlidosi (#)

Fr.: euclidien   

Of or pertaining to Euclid, or his postulates. → Euclidean division, → Euclidean geometry, → Euclidean space, → non-Euclidean geometry.

After the Gk. geometrician and educator at Alexandria, around 300 B.C., who applied the deductive principles of logic to geometry, thereby deriving statements from clearly defined axioms.

Euclidean division
  بخش ِ اقلیدوسی   
baxš-e Oqlidosi

Fr.: division euclidienne   

In arithmetic, the conventional process of division of two → integers. For a → real number a divided by b > 0, there exists a unique integer q and a real number r, 0 ≤ r <b, such that a = qb + r.

Euclidean; → division.

Euclidean geometry
  هندسه‌ی ِ اقلیدوسی   
hendese-ye Oqlidosi (#)

Fr.: géométrie euclidienne   

The geometry based on the postulates or descriptions of Euclid. One of the critical assumptions of the Euclidean geometry is given in his fifth postulate: through a point not on a line, one and only one line be drawn parallel to the given line. See also → non-Euclidean geometry.

Euclidean; → geometry.

Euclidean space
  فضای ِ اقلیدوسی   
fazâ-ye Oqlidosi

Fr.: espace euclidean   

A space in which the → distance between any two points is given by the → Pythagorean theorem: d2 = (Δx)2 + (Δy)2 + (Δz)2, where d is distance and Δx, Δy, and Δz are differential → Cartesian coordinates. Euclidean n-space Rn is the set of all column vectors with n real entries.

Euclidean; → space.

Eudoxan spheres
  سپهرهای ِ اءودوکسوس   
sepehrhâ-ye Eudoxus

Fr.: sphères d'Eudoxe   

spheres of Eudoxus.

spheres of Eudoxus.


Fr.: Euler   

Leonhard Euler (1707-1783), the eminent Swiss mathematician, physicist, and astronomer.

Euler equation
  هموگش ِ اویلر   
hamugeš-e Euler

Fr.: équation d'Euler   

In → fluid mechanics, one of a set of → differential equations that govern the motion of a → compressible, → inviscid fluid. Euler equations correspond to the → Navier-Stokes equations with zero → viscosity.

Euler; → equation.

Euler line
  خط ِ اویلر   
xatt-e Euler

Fr.: droite d'Euler   

In any → triangle, the straight line on which always lie the → centroid, → circumcenter, and → orthocenter.

Euler; → line.

Euler's broken line
  خط ِ شکسته‌ی ِ اویلر   
xatt-e šekaste-ye Euler

Fr.: ligne brisée   

The line drawn in a coordinate plane connecting the approximate values of the solution of a → first-order differential equation.

Euler; → broken line.

Euler's formula
  دیسول ِ اویلر   
disul-e Euler

Fr.: formule d'Euler   

A formula which expresses an → exponential function with an → imaginary number  → exponent in terms of → trigonometric functions:
e = cos θ + i sinθ,
e-iθ = cos θ - i sinθ,
cosθ = (e + e-iθ)/2,
sinθ = (e - e-iθ)/2i.
In the particular case of θ = π, Euler's formula becomes: eiπ + 1 = 0, which is considered by many mathematicians to be the most elegant mathematical equation. → mathematical elegance.

Euler; → formula.

Eulerian method
  روش ِ اویلری   
raveš-e Euleri

Fr.: méthode eulérienne   

Fluid mechanics: A method in which the changes in the physical properties of the fluid, such as velocity, acceleration, and density are described at a fixed point in space occupied by the fluid. Compare with → Lagrangian method.

Euler; → method.

  خوشگویی، خوشزبانی   
xošguyi, xošzabâni

Fr.: euphémisme   

An inoffensive word or phrase substituted for one considered offensive or hurtful, especially one concerned with religion, sex, death, or excreta (

From Gk. euphemismos, from euphemizein "speak with fair words, use words of good omen," from → eu- "well," + pheme "speech, voice, talk," from phanai "to speak," ultimately from PIE *bha- "to speak, tell, say;" cf. Skt. bhanati "speaks;" L. fari "to say," fabula "tale, story," fama "talk, rumor, report; reputation;" Armenian ban, bay "word, term."

Xošguyi, xošzabâni, literally "pleasant talking, ~ speach," from xoš "well, pleasant," → eu- + guyi verbal noun of goftan "to say, talk, speak," → logic; zabâni, from zabân, → language.

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