doubleton vs dyad

doubleton and dyad both are nouns.

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

As nouns, dyad is a hypernym of doubleton; that is, dyad is a word with a broader meaning than doubleton:

doubleton: (bridge) a pair of playing cards that are the only cards in their suit in the hand dealt to a player
dyad: two items of the same kind

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

doubleton (noun)	dyad (noun)
(bridge) a pair of playing cards that are the only cards in their suit in the hand dealt to a player	two items of the same kind