Surefire and Unsure

Surefire

Surefire adjective - Not likely to fail.

Unsure

Unsure adjective - Not feeling sure about the truth, wisdom, or trustworthiness of someone or something.

Surefire is an antonym for unsure.
Cite this Source
Unsure and Surefire. (2016). Retrieved 2026, August 13, from https://thesaurus.plus/related/surefire/unsure
Surefire & Unsure. N.p., 2016. Web. 13 Aug. 2026. <https://thesaurus.plus/related/surefire/unsure>.
Unsure or Surefire. 2016. Accessed August 13, 2026. https://thesaurus.plus/related/surefire/unsure.
Google Ngram Viewer shows how "surefire" and "unsure" have occurred on timeline