incidental vs plural form

incidental and plural form both are nouns.

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

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

incidental (adjective)	plural form (adjective)
(sometimes followed by `to') minor or casual or subordinate in significance or nature or occurring as a chance concomitant or consequence
not of prime or central importance
occurring with or following as a consequence