Mendacious \Men*da"cious\, a. [L. mendax, -acis, lying, cf. mentiri to lie.] 1. Given to deception or falsehood; lying; as, a mendacious person. [1913 Webster] 2. False; counterfeit; containing falsehood; as, a mendacious statement. [1913 Webster] -- {Men*da"cious*ly}, adv. -- {Men*da"cious*ness}, n. [1913 Webster]