It will come as no surprise that fallacious is related to the noun fallacy, meaning “delusion” or “falsehood.” Both words come from the Latin word fallacia, which in turn comes from fallere, …

FALLACIOUS definition: containing a fallacy; logically unsound. See examples of fallacious used in a sentence.

To unquestioningly adhere to traditional policies when there is good reason for change can be regarded as a fallacious appeal to authority.

Definition of fallacious adjective in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

If an idea, argument, or reason is fallacious, it is wrong because it is based on a fallacy.

1. Containing or based on a fallacy: a fallacious assumption. 2. Tending to mislead; deceptive: fallacious testimony.

There are five meanings listed in OED's entry for the adjective fallacious, one of which is labelled obsolete. See ‘Meaning & use’ for definitions, usage, and quotation evidence.

Sep 10, 2025 · fallacious (comparative more fallacious, superlative most fallacious) Characterized by fallacy; false or mistaken. synonyms, antonyms hyponyms quotations

Definition of fallacious. English dictionary and integrated thesaurus for learners, writers, teachers, and students with advanced, intermediate, and beginner levels.

Something fallacious is a mistake that comes from too little information or unsound sources. Predictions that the whole state of California will snap off from the rest of North America and …