What is another word for "conjugate"?

Roget's Thesaurus (1911) lists these synonyms for "conjugate": and, artillery, biformity, binary, binate, binomial, biparous, biplicity, both, brace, bracket, concordance, conduplicate, conjugation, couple, delectus, derivation, derivative, deuce, dictionary, double, doublets, dual, dualism, dualistic, duality, duet, duplex, duplicity, dyad, dyadic, etymology, etymon, exactly, gemini, glossary, glossographer, glossology, gradus, grammar.