Source : WordNet®

duplicitous
     adj : marked by deliberate deceptiveness especially by pretending
           one set of feelings and acting under the influence of
           another; "she was a deceitful scheming little thing"-
           Israel Zangwill; "a double-dealing double agent"; "a
           double-faced infernal traitor and schemer"-
           W.M.Thackeray [syn: {ambidextrous}, {deceitful}, {double-dealing},
            {Janus-faced}, {two-faced}, {double-faced}, {double-tongued}]