PA system vs P.A.

PA system and P.A. both are nouns.

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

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

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

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

PA system (noun)	P.A. (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