brethren vs plural

brethren and plural both are nouns.

Word	Noun	Adjective	Verb	Adverb
brethren	Yes	No	No	No
plural	Yes	Yes	No	No

brethren (noun)	plural (noun)
(plural) the lay members of a male religious order	the form of a word that is used to denote more than one

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