Doubtful and Fail-safe
Opposite meaning words
Doubtful
Doubtful adjective - Not feeling sure about the truth, wisdom, or trustworthiness of someone or something.
Fail-safe
Fail-safe adjective - Not likely to fail.
Usage example: men have traditionally regarded flowers as the fail-safe gift for Valentine's Day
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Synonyms for Fail-safe
Cite this Source
Fail-safe and Doubtful. (2016). Retrieved 2026, August 13, from https://thesaurus.plus/related/doubtful/fail-safe
Doubtful & Fail-safe. N.p., 2016. Web. 13 Aug. 2026. <https://thesaurus.plus/related/doubtful/fail-safe>.
Fail-safe or Doubtful. 2016. Accessed August 13, 2026. https://thesaurus.plus/related/doubtful/fail-safe.
