widow's weeds vs plural

widow's weeds and plural both are nouns.

Word	Noun	Adjective	Verb	Adverb
widow's weeds	Yes	No	No	No
plural	Yes	Yes	No	No

widow's weeds (noun)	plural (noun)
a black garment (dress) worn by a widow as a sign of mourning	the form of a word that is used to denote more than one

widow's weeds (adjective)	plural (adjective)
	grammatical number category referring to two or more items or units
	composed of more than one member, set, or kind