dev·il·ish / ˈdevəlish/ • adj. of, like, or appropriate to a devil in evil and cruelty: devilish tortures. ∎ mischievous and rakish: a wide, devilish grin. ∎ very difficult to deal with or use: it turned out to be a devilish job.• adv. inf., dated very; extremely: a devilish clever chap.DERIVATIVES: dev·il·ish·ness n.