blue jeans vs plural

blue jeans and plural both are nouns.

Word	Noun	Adjective	Verb	Adverb
blue jeans	Yes	No	No	No
plural	Yes	Yes	No	No

blue jeans (noun)	plural (noun)
(used in the plural) close-fitting trousers of heavy denim for manual work or casual wear	the form of a word that is used to denote more than one

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