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.

An atmosphere of cold oxygen. --Miller.

2. A supposed medium around various bodies; as, electrical atmosphere, a medium formerly supposed to surround electrical bodies. --Franklin.

3. The pressure or weight of the air at the sea level, on a unit of surface, or about 14.7 Ibs. to the sq. inch.

Hydrogen was liquefied under a pressure of 650 atmospheres. --Lubbock.

4. Any surrounding or pervading influence or condition.

The chillest of social atmospheres. --Hawthorne.

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.

Source: Webster's Revised Unabridged Dictionary (1913)