- mendacious
- 1610s, from M.Fr. mendacieux, from L. mendacium "a lie," from mendax (gen. mendacis) "lying, deceitful," related to menda "fault, defect, carelessness in writing" (cf. amend, mendicant), from PIE base *mend- "physical defect, fault." The sense evolution of mendax influenced by mentiri "to speak falsely, lie, deceive."