Indubitable and Sure

Indubitable

Indubitable adjective - Not capable of being challenged or proved wrong.
Usage example: the indubitable fact that there are no more woolly mammoths or saber-toothed tigers around

Sure is a synonym for indubitable in certain topic. In some cases you can use "Sure" instead an adjective "Indubitable", when it comes to topics like unquestionable, undoubted.

Nearby Word: indubitably

Sure

Sure adjective - Not capable of being challenged or proved wrong.
Usage example: no sure evidence that life exists on other planets

Indubitable is a synonym for sure in certain topic. You can use "Indubitable" instead an adjective "Sure", if it concerns topics such as unquestionable.

Nearby Word: surely
Cite this Source
Sure and Indubitable. (2016). Retrieved 2026, August 15, from https://thesaurus.plus/related/indubitable/sure
Indubitable & Sure. N.p., 2016. Web. 15 Aug. 2026. <https://thesaurus.plus/related/indubitable/sure>.
Sure or Indubitable. 2016. Accessed August 15, 2026. https://thesaurus.plus/related/indubitable/sure.
Google Ngram Viewer shows how "indubitable" and "sure" have occurred on timeline