Impossible
Impossible adjective - Incapable of being solved or accomplished.
Usage example: fitting everything in my backpack seemed an impossible task
Unbelievable is a synonym for impossible in incredible topic. In some cases you can use "Unbelievable" instead an adjective "Impossible", when it comes to topics like unimaginable. popular alternative
Nearby Words: impossibility, impossibly
Unbelievable
Unbelievable adjective - Too extraordinary or improbable to believe.
Usage example: a completely unbelievable story about why there was lipstick on his collar
Impossible is a synonym for unbelievable in unconvincing topic. You can use "Impossible" instead an adjective "Unbelievable", if it concerns topics such as unimaginable, beyond the imagination. popular alternative
Nearby Words: unbelieving, unbeliever
Mutual synonyms
Related pairs
- questionable and impossible
- questionable and unbelievable
- outlandish and impossible
- outlandish and unbelievable
- doubtful and impossible
- doubtful and unbelievable
- outrageous and impossible
- outrageous and unbelievable
- implausible and impossible
- implausible and unbelievable
- incredible and impossible
- incredible and unbelievable
- fantastic and impossible
- fantastic and unbelievable
Both words in one sentence
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Not a completely impossible storyline, but still fairly unbelievable due to Michaels' undoubtedly astronomical salary as a WWE veteran.
Source: Wrestling Doesn't Pay -
We've all seen people hit impossible targets at great lengths under unbelievable circumstances.
Source: Accidental Aiming Skills -
A tall tale is a story with unbelievable or outright impossible elements (such as an impossibly tall man, hence the name "tall" tale), told as if it were true and factual.
Source: Tall Tale
Cite this Source
Unbelievable and Impossible. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/impossible/unbelievable
Impossible & Unbelievable. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/impossible/unbelievable>.
Unbelievable or Impossible. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/impossible/unbelievable.
Google Ngram Viewer shows how "impossible" and "unbelievable" have occurred on timeline