devilish
1. [ adjective ] showing the cunning or ingenuity or wickedness typical of a devil
Synonyms: diabolical mephistophelian mephistophelean diabolic
Examples:

"devilish schemes" "the cold calculation and diabolic art of some statesmen" "the diabolical expression on his face" "a mephistophelian glint in his eye"

Related terms: evil
2. [ adverb ] in a playfully devilish manner
Synonyms: devilishly
Examples:

"the socialists are further handicapped if they believe that capitalists are not only wicked but also devilishly clever"

3. [ adjective ] playful in an appealingly bold way
Synonyms: roguish rascally
Examples:

"a roguish grin"

Related terms: playful
Similar spelling:   devilishly
  devilise
  devilize
  Debellis