THESAURUS
dyad
both, brace, couple, couplet, distich, double harness, doublet, duad, duet, duo, match, mates, pair, set of two, span, team, the two, twain, two, twosome, yoke
ROGET THESAURUS
dyad
Duality
N
duality, dualism, duplicity, biplicity, biformity, polarity, two, deuce, couple, duet, brace, pair, cheeks, twins, Castor and Pollux, gemini, Siamese twins, fellows, yoke, conjugation, dispermy, doublets,
dyad, span, two, twin, dual, dualistic, double, binary, binomial, twin, biparous, dyadic, conduplicate, duplex, biduous, binate, diphyletic, dispermic, unijugate, tete-a-tete, coupled, conjugate, both, both the one and the other.