headquarters vs plural

headquarters and plural both are nouns.

Word	Noun	Adjective	Verb	Adverb
headquarters	Yes	No	No	No
plural	Yes	Yes	No	No

headquarters (noun)	plural (noun)
the military installation from which a commander performs the functions of command	the form of a word that is used to denote more than one
(usually plural) the office that serves as the administrative center of an enterprise
(plural) a military unit consisting of a commander and the headquarters staff

headquarters (adjective)	plural (adjective)
	grammatical number category referring to two or more items or units
	composed of more than one member, set, or kind