HELLISH Meaning of HELLISH in English adj. & adv. --adj. 1. of or like hell. 2 colloq. extremely difficult or unpleasant. --adv. Brit. colloq. (as an intensifier) extremely (hellish expensive). Derivatives: hellishly adv. hellishness n. Oxford English vocab. Оксфордский английский словарь. 2012