twosome vs dyad

twosome and dyad both are nouns.

Word	Noun	Adjective	Verb	Adverb
twosome	Yes	No	No	No
dyad	Yes	No	No	No

As nouns, twosome and dyad are synonyms defined as:

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

twosome (noun)	dyad (noun)
a pair who associate with one another	two items of the same kind
two items of the same kind