Doubtful
Insoluble
Insoluble adjective - Incapable of being solved or accomplished.
Usage example: the seemingly insoluble mystery concerning the identity of the people who built these ancient structures
Doubtful and insoluble are semantically related. Sometimes you can use "Doubtful" instead an adjective "Insoluble".
Nearby Word: insolubility
Mutual synonyms
Related pairs
- obscure and doubtful
- obscure and insoluble
- ambiguous and doubtful
- ambiguous and insoluble
- incredible and doubtful
- incredible and insoluble
- indeterminate and doubtful
- indeterminate and insoluble
- equivocal and doubtful
- equivocal and insoluble
- impossible and doubtful
- impossible and insoluble
- indecisive and doubtful
- indecisive and insoluble
Cite this Source
Insoluble and Doubtful. (2016). Retrieved 2026, July 28, from https://thesaurus.plus/related/doubtful/insoluble
Doubtful & Insoluble. N.p., 2016. Web. 28 Jul. 2026. <https://thesaurus.plus/related/doubtful/insoluble>.
Insoluble or Doubtful. 2016. Accessed July 28, 2026. https://thesaurus.plus/related/doubtful/insoluble.
Google Ngram Viewer shows how "doubtful" and "insoluble" have occurred on timeline