deuce vs couplet

deuce and couplet both are nouns.

Word	Noun	Adjective	Verb	Adverb
deuce	Yes	No	No	No
couplet	Yes	No	No	No

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

deuce: the cardinal number that is the sum of one and one or a numeral representing this number
couplet: two items of the same kind

Other hyponyms of deuce include craps, snake eyes, brace, couple, distich, duad, duet, duo, dyad, pair, span, twain, twosome, yoke.

deuce (noun)	couplet (noun)
one of the four playing cards in a deck that have two spots	a stanza consisting of two successive lines of verse; usually rhymed
a word used in exclamations of confusion	two items of the same kind
the cardinal number that is the sum of one and one or a numeral representing this number
a tie in tennis or table tennis that requires winning two successive points to win the game