atmo

Etymology
From.

Noun

 * 1)  The standard atmospheric pressure used in certain physical measurements and calculations; conventionally, that pressure under which the barometer stands at 760 millimeters, at a temperature of 0&deg; Centigrade, at the level of the sea, and in the latitude of Paris.
 * 2) * 1880?, Heat
 * under a constant pressure of one atmo
 * 1)  atmosphere (of a planet)