Entry 1 sense Webster, 1913 duplicitous · du·plic·i·tous · IPA /duːˈplɪsətəs/ 01 adj. exhibiting duplicity{2}; deceitful; double-dealing. 1. exhibiting duplicity{2}; deceitful; double-dealing. Syn. ambidextrous, deceitful, double-dealing, two-faced.