(n.) Division into two parts, esp. two equal parts.

Janus L ambiguity ambivalence angle apex arborescence arborization bend bifidity biforking biformity bight bipartition bisection branching branching off by two cant chevron coin conjugation corner crank crook crotchet cutting in two deflection dichotomy dimidiation divarication division dogleg doubleness doublethink doubling dualism duality duplexity duplication duplicity elbow ell equivocality fork forking furcation halving hook in half inflection irony knee nook pairing point polarity quoin ramification subdivision swerve treelikeness trifurcation twinning two-facedness twoness veer vertex zag zig zigzag