antiaircraft gun vs pom-pom

antiaircraft gun and pom-pom both are nouns.

Word	Noun	Adjective	Verb	Adverb
antiaircraft gun	Yes	No	No	No
pom-pom	Yes	No	No	No

As nouns, antiaircraft gun and pom-pom are synonyms defined as:

antiaircraft gun and pom-pom: artillery designed to shoot upward at airplanes

Other synonyms of antiaircraft gun include ack-ack, ack-ack gun, antiaircraft, flack, flak.

antiaircraft gun (noun)	pom-pom (noun)
artillery designed to shoot upward at airplanes	artillery designed to shoot upward at airplanes
	decoration consisting of a ball of tufted wool or silk; usually worn on a hat