stacks vs plural

stacks and plural both are nouns.

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

stacks (noun)	plural (noun)
storage space in a library consisting of an extensive arrangement of bookshelves where most of the books are stored	the form of a word that is used to denote more than one
a large number or amount

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