Main Entry: dreadful ?[dred-fuhl] Part of Speech: adjective Definition: horrible, frightening Synonyms: abominable, alarming, appalling, atrocious, awful, bad, beastly, creepy*, dire, distressing, fearful, formidable, frightful, frozen, ghastly, godawful, grievous, grim, grody, gross*, hideous, horrendous, horrific, icky, lousy, mean, monstrous, rotten, shameful, shocking, shuddersome, spooky, terrible, terrific, tragic, tremendous, wicked