pair of trousers vs plural

pair of trousers and plural both are nouns.

Word	Noun	Adjective	Verb	Adverb
pair of trousers	Yes	No	No	No
plural	Yes	Yes	No	No

pair of trousers (noun)	plural (noun)
(usually in the plural) a garment extending from the waist to the knee or ankle, covering each leg separately	the form of a word that is used to denote more than one

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