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}]