Source : Webster's Revised Unabridged Dictionary (1913)

Guileful \Guile"ful\, a.
   Full of guile; characterized by cunning, deceit, or
   treachery; guilty. -- {Guile"ful*ly}, adv. --
   {Guile"ful*ness}, n.

Source : WordNet®

guileful
     adj : marked by skill in deception; "cunning men often pass for
           wise"; "deep political machinations"; "a foxy scheme";
           "a slick evasive answer"; "sly as a fox"; "tricky Dik";
           "a wily old attorney" [syn: {crafty}, {cunning}, {dodgy},
            {foxy}, {knavish}, {slick}, {sly}, {tricksy}, {tricky},
            {wily}]