[fuh-ley-shuh s]


containing a fallacy; logically unsound: fallacious arguments.
deceptive; misleading: fallacious testimony.
disappointing; delusive: a fallacious peace.

Nearby words

  1. fall, albert bacon,
  2. fall, the,
  3. fall-off,
  4. falla,
  5. falla, manuel de,
  6. fallaciously,
  7. fallacy,
  8. fallacy of composition,
  9. fallacy of division,
  10. fallacy of many questions

Origin of fallacious

First recorded in 1500–10, fallacious is from the Latin word fallāciōsus deceitful, deceptive. See fallacy, -ous

Related forms
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for fallacious

British Dictionary definitions for fallacious



containing or involving a fallacy; illogical; erroneous
tending to mislead
delusive or disappointinga fallacious hope
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.

Online Etymology Dictionary, © 2010 Douglas Harper