9 letters · 15 points in Scrabble
adjective intended to deceive; ; ; - S.T.Coleridge
adjective marked by deliberate deceptiveness especially by pretending one set of feelings and acting under the influence of another; - Israel Zangwill; ; - W.M.Thackeray
originFrom deceit + -ful.
Etymology from Wiktionary, CC BY-SA 3.0