A prefix meaning "resembling, almost, having some, but not all of the features of."
From L. quasi "as if, as though," from qua(m)" as" + si "if."
Cunân "so, like that; just as if," from cun "how?," (Mid.Pers. cigôn "how?," cigônêh "nature, character," O.Pers/Av. ci- "what, any," collateral stem to ka- "who?, what?;" cf. Skt. ka-; Gk. po-; L. quo-; E. what, who; PIE *qwos/*qwes) + suffix ân. -vaš a suffix of similitude.
A system in which the nuclei of two colliding atoms approach each other closely for a brief lapse of time so that their electrons are arranged in atomic orbitals characteristic of a single atom with combined atomic number.
Fr.: sous-système quasi-fermé
A subsystem if its intrinsic energy is large, on the average, with respect to the energy of its interaction with other portions of the → closed system.
Fr.: théorie quasi-linéaire
In plasma physics, the theory that considers the interactions between waves and particles are of first order only. It ignores all terms of second order in the fluctuating quantities.
An asteroid moving around the Sun having the same mean motion and mean → longitude as a planet, but a different → eccentricity. The asteroid remains near the planet much like a satellite even when its distance is large enough so that it is well outside the planet's → Hill sphere. The quasi-satellite motion is one class of possible → co-orbital motions of small bodies in 1:1 mean-motion → resonance with a planet. If the quasi-satellite orbit is coplanar with the planet, then the motion is stable in the → secular approximation. When the orbits are inclined enough, an asteroid can be trapped into such a motion for a finite period of time. Earth has several quasi-satellites (mainly 3753 Cruithne, 2002 AA29, 2003 YN107), also does Venus (the only one so far discovered, 2002 VE68). The possibility of such orbits was first suggested by J. Jackson (1913, MNRAS 74, 62).
quasi-separatrix layer (QSL)
Fr.: couche quasi-séparatrice
A region of the solar atmosphere where the gradient of the field line → linkage from one boundary to another is large so that the field lines can slip-run rapidly through the → plasma. The QSL results from → magnetic reconnection without → null point.
A model of radiative transfer that ignores forward scattering of photons; assuming forward-scattered light as un-scattered.
Fr.: objet quasi-stellaire
Initial name of → quasars.
quasi-stellar radio source
râdio-xan-e cunân setâré, ~ ~ setâré-vaš
Fr.: radiosource quasi-stellaire
A quasar with detectable radio emission.