Fallacious and Illogical

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

Illogical is a synonym for fallacious in correct topic. In some cases you can use "Illogical" instead an adjective "Fallacious", when it comes to topics like false, invalid, null and void, incorrect. popular alternative

Illogical

Illogical adjective - Not using or following good reasoning.
Usage example: illogical people are likely to believe every sensational claim made on TV

Fallacious is a synonym for illogical in correct topic. You can use "Fallacious" instead an adjective "Illogical", if it concerns topics such as irrational, invalid, null and void, incorrect. popular alternative

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