duplicitous

from WordNet (r) 3.0 (2006)

duplicitous
    adj 1: 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}, {duplicitous}, {Janus-faced}, {two-faced},
           {double-faced}, {double-tongued}]

from The Collaborative International Dictionary of English v.0.48

duplicitous \du*plic"i*tous\ adj.
   exhibiting duplicity[2]; deceitful; double-dealing.

   Syn: ambidextrous, deceitful, double-dealing, two-faced.
        [WordNet 1.5]