Reasonable and Unsubstantiated
Opposite meaning words
Reasonable
Reasonable adjective - Based on sound reasoning or information.
Usage example: those playing rules sound reasonable to me
Unsubstantiated is an antonym for reasonable.
Unsubstantiated
Unsubstantiated adjective - Having no basis in reason or fact.
Usage example: an unsubstantiated claim that was thrown out of court
Reasonable is an antonym for unsubstantiated.
Nearby Word: unsubstantially
Cite this Source
Unsubstantiated and Reasonable. (2016). Retrieved 2026, August 16, from https://thesaurus.plus/related/reasonable/unsubstantiated
Reasonable & Unsubstantiated. N.p., 2016. Web. 16 Aug. 2026. <https://thesaurus.plus/related/reasonable/unsubstantiated>.
Unsubstantiated or Reasonable. 2016. Accessed August 16, 2026. https://thesaurus.plus/related/reasonable/unsubstantiated.
Google Ngram Viewer shows how "reasonable" and "unsubstantiated" have occurred on timeline