The Collaborative International Dictionary of English v.0.48:

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]