interest group vs plural form

interest group and plural form both are nouns.

Word	Noun	Adjective	Verb	Adverb
interest group	Yes	No	No	No
plural form	Yes	No	No	No

interest group (noun)	plural form (noun)
(usually plural) a social group whose members control some field of activity and who have common aims	the form of a word that is used to denote more than one