ROGET THESAURUS
castor and pollux
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.