THESAURUS
Janus, ambiguity, ambivalence, bifidity, biformity, bifurcation, bipartition, bisection, branching, by two, conjugation, cutting in two, dichotomy, dimidiation, division, doubleness, doublethink, doubling, dualism, duality, duplexity, duplication, duplicity, equivocality, forking, in half, irony, pairing, polarity, ramification, subdivision, twinning, two-facedness, twoness
ROGET THESAURUS
bisection
N
bisection, bipartition, dichotomy, subdichotomy,
halving, dimidiation, bifurcation, forking, branching, ramification, divarication, fork, prong, fold, half, moiety, bisected, cloven, cleft, bipartite, biconjugate, bicuspid, bifid, bifurcous, bifurcate, bifurcated, distichous, dichotomous, furcular, semi-, demi-, hemi.