Synonyms and related words :
Janus-like, ambidextrous, as much again, bifacial, bifold, biform, bilateral, binary, binate, biparous, bivalent, conduplicate, disomatous, double, double-barreled, double-faced, doubly, dual, dualistic, dually, duple, duplex, duplicate, dyadic, geminate, geminated, paired, second, secondary, twice, twice as much, twice over, twin, twinned, two times, two-faced, two-level, two-ply, two-sided, two-story