atm vs standard pressure

atm and standard pressure both are nouns.

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

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

atm and standard pressure: 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 atmosphere.

atm (noun)	standard pressure (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