(n.) A Latin deity represented with two faces looking in opposite directions. Numa is said to have dedicated to Janus the covered passage at Rome, near the Forum, which is usually called the Temple of Janus. This passage was open in war and closed in peace.

ambiguity ambivalence biformity bifurcation conjugation dichotomy doubleness doublethink doubling dualism duality duplexity duplication duplicity equivocality halving irony pairing polarity twinning two-facedness twoness