Atmo \At"mo\, n. [Contr. fr. atmosphere.] (Physics)
The standard atmospheric pressure used in certain physical
measurements 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. --Sir W. Thomson.
[1913 Webster] Atmologic