married couple vs mate

married couple and mate both are nouns.

Word	Noun	Adjective	Verb	Adverb
married couple	Yes	No	No	No
mate	Yes	No	Yes	No

married couple (noun)	mate (noun)
two people who are married to each other	a chess move constituting an inescapable and indefensible attack on the opponent's king
	an exact duplicate
	South American tea-like drink made from leaves of a South American holly called mate
	a person's partner in marriage
	the partner of an animal (especially a sexual partner)
	the officer below the master on a commercial ship
	informal term for a friend of the same sex
	a fellow member of a team
	South American holly; leaves used in making a drink like tea
	one of a pair

married couple (verb)	mate (verb)
	place an opponent's king under an attack from which it cannot escape and thus ending the game
	engage in sexual intercourse
	bring two objects, ideas, or people together