P.A. vs P.A. system

P.A. and P.A. system both are nouns.

Word	Noun	Adjective	Verb	Adverb
P.A.	Yes	No	No	No
P.A. system	Yes	No	No	No

As nouns, P.A. and P.A. system are synonyms defined as:

P.A. and P.A. system: an electronic amplification system used as a communication system in public areas

Other synonyms of P.A. include PA, PA system, public address system.

P.A. (noun)	P.A. system (noun)
an electronic amplification system used as a communication system in public areas	an electronic amplification system used as a communication system in public areas