Fr.: entraînement de l'éther
A hypothesis put forward to explain the null measurement of the → ether drift. According to this hypothesis, the Earth somehow drags the ether with it as our planet rotates on its axis and revolves around the Sun. However, the ether drag hypothesis contradicts results from several experiments, including the → aberration of starlight.
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.
A combining form meaning "race, culture, people."
From Gk. ethnos "people, nation, class, tribe."
Qowm- loan from Ar. qaum "people, tribe, family."
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.
The study of specific cultures (ethnic groups) in their different aspects (anthropological, social, cultural, etc.) to establish similarities and disparities between them.
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.
etil alkol (#)
Fr.: éthyl alcool
Same as → ethanol.
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.
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.
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.
Fr.: division euclidienne
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.
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.
Fr.: sphères d'Eudoxe
Leonhard Euler (1707-1783), the eminent Swiss mathematician, physicist, and astronomer.
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.
Fr.: droite d'Euler
Euler's broken line
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.
Fr.: formule d'Euler
A formula which expresses an → exponential function
with an → imaginary number
→ exponent in terms of
→ trigonometric functions:
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.