pair vs couple

pair and couple both are nouns.

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

As nouns, couple is a hyponym of pair; that is, couple is a word with a more specific, narrower meaning than pair:

Other hyponyms of pair include duet, duo, twosome, yoke.

As nouns, pair and couple are synonyms defined as:

Other synonyms of pair include brace, couplet, distich, duad, duet, duo, dyad, span, twain, twosome, yoke.

As verbs, pair and couple are synonyms defined as:

Other synonyms of pair include copulate, mate.

As verbs, pair and couple are synonyms defined as:

Other synonyms of pair include match, mate, twin.

As verbs, pair and couple are synonyms defined as:

Other synonyms of pair include pair off, partner off.

pair (noun)	couple (noun)
two people considered as a unit	a pair who associate with one another
a set of two similar things considered as a unit	a pair of people who live together
a poker hand with 2 cards of the same value	(physics) something joined by two equal and opposite forces that act along parallel lines
two items of the same kind	two items of the same kind
	a small indefinite number

pair (verb)	couple (verb)
engage in sexual intercourse	engage in sexual intercourse
bring two objects, ideas, or people together	link together
arrange in pairs	bring two objects, ideas, or people together
occur in pairs	form a pair or pairs
form a pair or pairs