plural vs incidental

plural and incidental both are nouns.

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

plural (noun)	incidental (noun)
the form of a word that is used to denote more than one	an item that is incidental
	(frequently plural) an expense not budgeted or not specified

plural (adjective)	incidental (adjective)
grammatical number category referring to two or more items or units	(sometimes followed by `to') minor or casual or subordinate in significance or nature or occurring as a chance concomitant or consequence
composed of more than one member, set, or kind	not of prime or central importance
	occurring with or following as a consequence