Roget's Thesaurus of English Words and Phrases by Peter Mark Roget

polarity. two, deuce, couple, duet, brace, pair, cheeks, twins, Castor and Pollux, gemini, Siamese twins; fellows; yoke, conjugation; dispermy†, doublets, dyad, span. V. pair [unite in pairs], couple, bracket, yoke; conduplicate†; mate, span [U.S.]. Adj. two, twin; dual, dualistic, double; binary, binomial; twin, biparous†; dyadic [Math.]; conduplicate†; duplex &c 90; biduous†, binate†, diphyletic†, dispermic†, unijugate†; tete-a-tete. coupled &c v.; conjugate. both, both the one and the other.