From WordNet (r) 2.0 (August 2003) [wn]:
atmosphere
n 1: a particular environment or surrounding influence; "there
was an atmosphere of excitement" [syn: ambiance,
ambience]
2: a unit of pressure: the pressure that will support a column
of mercury 760 mm high at sea level and 0 degrees
centigrade [syn: standard atmosphere, atm, {standard
pressure}]
3: the mass of air surrounding the Earth; "there was great heat
as the comet entered the atmosphere"; "it was exposed to
the air" [syn: air]
4: the weather or climate at some place; "the atmosphere was
thick with fog" [syn: atmospheric state]
5: the envelope of gases surrounding any celestial body
6: a distinctive but intangible quality surrounding a person or
thing; "an air of mystery"; "the house had a neglected
air"; "an atmosphere of defeat pervaded the candidate's
headquarters"; "the place had an aura of romance" [syn:
air, aura]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Atmosphere \At"mos*phere\, n. [Gr. ? vapor (akin to Skr.
[=a]tman breath, soul, G. athem breath) + ? sphere: cf. F.
atmosph[`e]re. See Sphere.]
1. (Physics)
(a) The whole mass of a["e]riform fluid surrounding the
earth; -- applied also to the gaseous envelope of any
celestial orb, or other body; as, the atmosphere of
Mars.
(b) Any gaseous envelope or medium.
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An atmosphere of cold oxygen. --Miller.
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2. A supposed medium around various bodies; as, electrical
atmosphere, a medium formerly supposed to surround
electrical bodies. --Franklin.
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3. The pressure or weight of the air at the sea level, on a
unit of surface, or about 14.7 lbs. to the sq. inch.
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Hydrogen was liquefied under a pressure of 650
atmospheres. --Lubbock.
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4. Any surrounding or pervading influence or condition.
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The chillest of social atmospheres. --Hawthorne.
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5. The portion of air in any locality, or affected by a
special physical or sanitary condition; as, the atmosphere
of the room; a moist or noxious atmosphere.
[1913 Webster] Atmospheric