• synonyms


[fuh-ley-shuh s]
See more synonyms for fallacious on Thesaurus.com
  1. containing a fallacy; logically unsound: fallacious arguments.
  2. deceptive; misleading: fallacious testimony.
  3. disappointing; delusive: a fallacious peace.
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Origin of fallacious

First recorded in 1500–10, fallacious is from the Latin word fallāciōsus deceitful, deceptive. See fallacy, -ous
Related formsfal·la·cious·ly, adverbfal·la·cious·ness, nounnon·fal·la·cious, adjectivenon·fal·la·cious·ly, adverbnon·fal·la·cious·ness, nounun·fal·la·cious, adjectiveun·fal·la·cious·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for fallacious

deceptive, delusive, erroneous, fictitious, fishy, fraudulent, illogical, illusory, incorrect, invalid, irrational, mad, misleading, mistaken, off, phony, spurious, unfounded, unreal, unreasonable

Examples from the Web for fallacious

Contemporary Examples of fallacious

Historical Examples of fallacious

  • Still, through this fallacious medium, a real enlargement of ideas is attained.

  • Only what must be avoided are fallacious inferences, my dear Lena—especially at this hour.


    Joseph Conrad

  • Political reconciliations are but outward and hollow, and fallacious.

    Apologia Pro Vita Sua

    John Henry Cardinal Newman

  • There has never been a religion too gross, too fallacious, to fail of followers.

  • No compromise for him, no evasions, no fallacious, unsecured promises to pay.

    Dream Days

    Kenneth Grahame

British Dictionary definitions for fallacious


  1. containing or involving a fallacy; illogical; erroneous
  2. tending to mislead
  3. delusive or disappointinga fallacious hope
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Derived Formsfallaciously, adverbfallaciousness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for fallacious


c.1500, from fallacy (Latin fallacia) + -ous. Related: Fallaciously; fallaciousness.

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Online Etymology Dictionary, © 2010 Douglas Harper