1520s, from Latin ambiguus "having double meaning, shifting, changeable, doubtful," adjective derived from ambigere "to dispute about, contend, debate," literally "to wander, go about, go around," figuratively "hesitate, waver, be in doubt," from ambi- "about" (from PIE root *ambhi- "around") + agere "drive, lead, act" (from PIE root *ag- "to drive, draw out or forth, move"). First attested in Sir Thomas More (1528); related ambiguity dates to c. 1400. Related: Ambiguously; ambiguousness.
