Extremely bad or unpleasant; terrible: had an awful day at the office. Commanding awe: "this sea, whose gently awful stirrings seem to speak of some hidden soul beneath\u201d ( Herman Melville). Filled with awe, especially: Filled with or displaying great reverence. Obsolete Afraid. Formidable in nature or extent: an awful burden; an awful risk. Informal Extremely; very: was awful sick.