Resembling, characteristic of, or pertaining to, the devil; diabolical; wicked in the extreme
emphasis You can use devilish to emphasize how extreme or difficult something is. a devilish puzzle. + devilishly dev·il·ish·ly It is devilishly painful
showing the cunning or ingenuity or wickedness typical of a devil; "devilish schemes"; "the cold calculation and diabolic art of some statesmen"; "the diabolical expression on his face"; "a mephistophelian glint in his eye"
in a playfully devilish manner; "the socialists are further handicapped if they believe that capitalists are not only wicked but also devilishly clever"