(adj) showing the cunning or ingenuity or wickedness typical of a devil, Syn. diabolic, mephistophelean, mephistophelian, diabolical, Example:devilish schemes; the cold calculation and diabolic art of some statesmen; the diabolical expression on his face; a mephistophelian glint in his eye
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
prop. a. Pertaining to, or resembling, the devil Mephistopheles, “a crafty, scoffing, relentless fiend;” devilish in character or aspect; crafty; showing cunning or ingenuity or wickedness; as, a mephistophelean glint in his eye. Syn. -- devilish, diabolic, diabolical, mephistophelean. [ 1913 Webster ]