Impossible
Impossible adjective - Incapable of being solved or accomplished.
Usage example: fitting everything in my backpack seemed an impossible task
Unthinkable is a synonym for impossible in unimaginable topic. In some cases you can use "Unthinkable" instead the word "Impossible" as an adjective or a noun, when it comes to topics like unbelievable, possible, unlikely, inconceivable. popular alternative
Nearby Words: impossibility, impossibly
Unthinkable
Unthinkable adjective - Too extraordinary or improbable to believe.
Usage example: to most people it seemed unthinkable that such a gentle man could be guilty of such awful crimes
Impossible is a synonym for unthinkable in unimaginable topic. You can use "Impossible" instead the word "Unthinkable" as an adjective or a noun, if it concerns topics such as incredible, unbelievable, possible, unlikely. popular alternative
Nearby Word: unthinking
Mutual synonyms
Related pairs
- implausible and impossible
- implausible and unthinkable
- hopeless and impossible
- hopeless and unthinkable
- incredible and impossible
- incredible and unthinkable
- unbelievable and impossible
- unbelievable and unthinkable
- improbable and impossible
- improbable and unthinkable
- absurd and impossible
- absurd and unthinkable
- unacceptable and impossible
- unacceptable and unthinkable
Both words in one sentence
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Tell your colleagues to do the possible, then the impossible, and then the unthinkable, until he's out of danger.
Source: Series / La Femme Nikita - But despite all this, turning down a King's gift was not only impossible but unthinkable.
- Consequently, this left them vulnerable to air attack when the unthinkable happened and Japanese planes began strafing and bombing them, which made fighting back against the attack almost impossible.
Source: Paranoia Fuel / Other
Cite this Source
Unthinkable and Impossible. (2016). Retrieved 2026, August 16, from https://thesaurus.plus/related/impossible/unthinkable
Impossible & Unthinkable. N.p., 2016. Web. 16 Aug. 2026. <https://thesaurus.plus/related/impossible/unthinkable>.
Unthinkable or Impossible. 2016. Accessed August 16, 2026. https://thesaurus.plus/related/impossible/unthinkable.
Google Ngram Viewer shows how "impossible" and "unthinkable" have occurred on timeline