dread·ful / ˈdredfəl/ • adj. causing or involving great suffering, fear, or unhappiness; extremely bad or serious: there's been a dreadful accident. ∎ extremely disagreeable: the weather was dreadful. ∎ used to emphasize the degree to which something is the case, esp. something regarded with sadness or disapproval: you're a dreadful flirt. ∎ (of a person or their feelings) troubled: I feel dreadful—I hate myself. ∎ (of a person or their appearance) feeling or looking ill: she looked dreadful and she was struggling for breath.DERIVATIVES: dread·ful·ness n.