atm vs standard atmosphere

atm and standard atmosphere both are nouns.

Word	Noun	Adjective	Verb	Adverb
atm	Yes	No	No	No
standard atmosphere	Yes	No	No	No

As nouns, atm and standard atmosphere are synonyms defined as:

atm and standard atmosphere: a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade

Other synonyms of atm include atmosphere, standard pressure.

atm (noun)	standard atmosphere (noun)
a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade	a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade