defensive vs antiaircraft

defensive and antiaircraft both are nouns.

Word	Noun	Adjective	Verb	Adverb
defensive	Yes	Yes	No	No
antiaircraft	Yes	Yes	No	No

defensive (noun)	antiaircraft (noun)
an attitude of defensiveness	artillery designed to shoot upward at airplanes

defensive (adjective)	antiaircraft (adjective)
intended or appropriate for defending against or deterring aggression or attack	designed for defense from a surface position against air attack
attempting to justify or defend in speech or writing