plural vs headquarters

plural and headquarters both are nouns.

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

plural (noun)	headquarters (noun)
the form of a word that is used to denote more than one	the military installation from which a commander performs the functions of command
	(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

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