bar- (#), dar- (#)
Adverb, used as prefix denoting "in, into, onto; toward; with continuous activity," etc.
O.E. on, variant of an "in, on, into," from P.Gmc. (cf. Du. aan, Ger. an, Goth. ana "on, upon"), from PIE base *ano "on" (cf. Av. ana "on," Gk. ana "on, upon," L. an-, O.C.S. na, Lith. nuo "down from").
Bar "on; up; upon; in; into; at; forth; with; near; before;
(Mid.Pers. abar; O.Pers.
upariy "above; over, upon, according to;" Av. upairi "above, over,"
upairi.zəma- "located above the earth;" cf. Gk. hyper- "over, above;"
L. super-; O.H.G. ubir "over;" PIE base *uper "over").
Fr.: en ligne
The state when two or more devices are directly connected and are communicating efficiently.
Fr.: réduction enligne
Preliminary reduction of observational data at a telescope simultaneously with their acquisition.
Fr.: observation sur la source
In comparison with → off-source observation, an observation which is concerned with the source itself.
on-the-spot (OTS) approximation
An approximation in the treatment of photoionized → H II regions, whereby secondary ionizing photons are absorbed immediately very close to their site of emission. The secondary photons, produced by → radiative recombinations directly to the → ground states, are thus ignored with respect to the ionizing photons emitted by the → exciting star. The OTS approximation requires that the ionized gas be sufficiently dense so that secondary ionizing photons are very likely absorbed within the H II region.
1) The smallest whole number, symbol 1; unity.
The → multiplicative identity for real and
O.E. an, from P.Gmc. *ainaz (cf. O.N. einn, Dan. een, O.Fris. an, Du. een, Ger. ein, Goth. ains), PIE base *oinos, cognate with Pers. yek, as below.
Yek "one, alone," from Mid.Pers. êwak, êv, yak, êk; cf. Baluci hivak "one, single" (Proto-Iranian *aiua-ka-); O.Pers. aiva- "one, alone;" Av. aēuua- "one, alone;" Skt. éka- "one, alone, single;" Gk. oios "alone, lonely;" L. unus "one;" E. one.
Fr.: écoulement uni-dimensionnel
A hypothetical flow in which all the flow parameters may be expressed as functions of time and one space coordinate only. This single space coordinate is usually the distance measured along the center-line of some conduit in which the fluid is flowing (B. Massey, Mechanics of Fluids, Taylor & Francis, 2006).
Fr.: correspondance un à un
A relationship between two distinct sets of elements such that every member of the first set can be paired with a unique element in the second set; and every member of the second set can be paired with a unique element in the first set. Two sets so related are said to be isomorphic.
A plant, Allium cepa, of the amaryllis family, having an edible, succulent, pungent bulb (Dictionary.com).
M.E., from Anglo-French union, O.Fr. oignon "onion," from L. unio-, also "pearl," literally "one, unity;" sense connection is the successive layers of an onion.
Mid.Pers. payâz, payâc; cf. Sogd. piyâk "onion," Yidgha piq, Vakhi piûk, Yazghulami piyeq, Kurd. pivaz; maybe related to PIE *peuk- "to prick, to sting, to stab," because of its pungent taste; cf. Gk. peukos "sting, prick, cusp, peak."
ivâz, tanhâ (#)
An adverb meaning without others or anything further; alone; solely; exclusively. → if and only if.
M.E., from O.E. anlic, from ân, → one.
Ivâz, from Mid.Pers. êvâz/êvâc, from Proto-Iranian
*aiua-ka-; cf. Pers. yek,
1) Classical philosophy: That part of metaphysics which is concerned with
the nature of existence or the essence of things.
From Mod.L. ontologia, from Gk. on (genitive ontos) "being" (pr.p. of einai "to be"), akin to L. esse "to be;" Pers. hastan, astan "to be," hasti "existence, being," as below; + -logia, → -logy.
abr-e Ort (#)
Fr.: nuage de Oort
Named after Jan Hendrik Oort (1900-1992), a Dutch astronomer who proposed its existence in 1950. He also made major contributions to our knowledge of the structure and rotation of the Milky Way Galaxy; → cloud.
Fr.: limite de Oort
1) The upper limit for the density of all matter in the plane of the Galaxy near the Sun's
locality, as calculated from the velocities and distribution of stars
in relation to the gravitational field of the Galactic disk. The value is
0.14 solar masses per cubic parsec, or 9.5 x 10-24 g cm3.
Fr.: minimum de Oort
Fr.: constantes de Oort
Two parameters, denoted A and B, that describe the major features of our Galaxy's differential rotation in the Sun's neighbourhood. A is one-half of the shear and equal to +14.4 ± 1.2 km s-1 kpc-1, and B, one-half of the vorticity, equal to -12.0 ± 2.8 km s-1 pc-1.
1) General: The state or quality of being opaque.
From Fr. opacité, from L. opacitatem (nom. opacitas) "shade, shadiness," from opacus "shaded, dark, opaque."
Kederi, from keder "opaque," from Ar. kader + -i suffix forming nouns from adjectives.
M.E., from M.Fr. opalle, from L. opalus, from Gk. opallios "opal, gem;" probably from a source akin to Skt. upala "jewel, precious stone."
Loan from E., as above.
1) The state of being → opalescent, or
emitting an → iridescence like that of
Exhibiting a play of colors like that of the opal.
Not permitting a radiation to pass through.
Adj. form of → opacity.