frightful /ˈfɹaɪtfəl/adjective 6adverb 1forms 3 adjective6 •Full of something causing fright, whether •Unpleasant, dreadful, awful (also used as an intensifier).Francis Urquhart: What a frightful little man. Where do they find them these days? Tim Stamper: God knows. If I had a dog like that, I'd shoot it. Francis Urquhart: Well, yes. Quite. — 1990 •Genuinely horrific, awful, or alarming. •(no longer used) Full of fright, whether •(no longer used) Afraid, frightened. •(no longer used) Timid, fearful, easily frightened.See how the frightful herds run from the wood. — 1613 adverb1 •(dialect) Frightfully; very.You had a lot of frightful good quotes. You must know half the books that there are. — 1926 formsfrightfuller · more frightful · most frightful