- 1 used to emphasize how good, bad, or extreme something is synonym incredible We had an unbelievable (= very good) time in Paris. Conditions in the prison camp were unbelievable (= very bad). We go through an unbelievable amount of food each week. The cold was unbelievable (= it was extremely cold). It's unbelievable that (= very shocking) they have permitted this trial to go ahead.
- 2very difficult to believe and unlikely to be true synonym incredible I found the whole story bizarre, not to say unbelievable. opposite believable
unbelievablyjump to other results
NAmE//ˌʌnbɪˈlivəbli//adverb unbelievably bad/good Unbelievably it actually works.