Fallacious and Well-founded
Opposite meaning words
Fallacious
Fallacious adjective - Not using or following good reasoning.
Usage example: it's fallacious to say that something must exist because science hasn't proven its nonexistence
Well-founded is an antonym for fallacious.
Well-founded
Well-founded adjective - According to the rules of logic.
Usage example: even a well-founded argument can lead to an erroneous conclusion if one of the premises is incorrect
Fallacious is an antonym for well-founded.
Cite this Source
Well-founded and Fallacious. (2016). Retrieved 2026, August 13, from https://thesaurus.plus/related/fallacious/well-founded
Fallacious & Well-founded. N.p., 2016. Web. 13 Aug. 2026. <https://thesaurus.plus/related/fallacious/well-founded>.
Well-founded or Fallacious. 2016. Accessed August 13, 2026. https://thesaurus.plus/related/fallacious/well-founded.
