mismatch vs pair

mismatch and pair both are nouns.

Word	Noun	Adjective	Verb	Adverb
mismatch	Yes	No	Yes	No
pair	Yes	No	Yes	No

As verbs, pair is a hypernym of mismatch; that is, pair is a word with a broader meaning than mismatch:

Other hypernyms of mismatch include couple, match, mate, twin.

mismatch (noun)	pair (noun)
a bad or unsuitable match	two people considered as a unit
	a set of two similar things considered as a unit
	a poker hand with 2 cards of the same value
	two items of the same kind

mismatch (verb)	pair (verb)
match badly; match two objects or people that do not go together	engage in sexual intercourse
	bring two objects, ideas, or people together
	arrange in pairs
	occur in pairs
	form a pair or pairs