fallacy

[ fal-uh-see ]

/ ˈfæl ə si /

Save This Word!

See synonyms for: fallacy / fallacies on Thesaurus.com

noun, plural fal·la·cies.

a deceptive, misleading, or false notion, belief, etc.: That the world is flat was at one time a popular fallacy.

a misleading or unsound argument.

deceptive, misleading, or false nature; erroneousness.

Logic. any of various types of erroneous reasoning that render arguments logically unsound.

Obsolete. deception.

OTHER WORDS FOR fallacy

1 misconception, delusion, misapprehension.

See synonyms for fallacy on Thesaurus.com

QUIZ

CAN YOU ANSWER THESE COMMON GRAMMAR DEBATES?

There are grammar debates that never die; and the ones highlighted in the questions in this quiz are sure to rile everyone up once again. Do you know how to answer the questions that cause some of the greatest grammar debates?

Question 1 of 7

Which sentence is correct?

His boss, whom he admires, is waiting to meet with him about the big project.

His boss, who he admires, is waiting to meet with him about the big project.

TAKE THE QUIZ TO FIND OUT

Origin of fallacy

1350–1400; <Latin fallācia a trick, deceit, equivalent to fallāc- (stem of fallāx) deceitful, fallacious + -ia-y³; replacing Middle English fallace<Middle French

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use fallacy in a sentence

These are the facts to rebut just a few of the fallacies I read on a daily basis about our party.
The Truth About Yisrael Beytenu|Hamad Amar|November 9, 2012|DAILY BEAST
Masood Aziz outlines six fallacies they perpetuate about the US engagement in Afghanistan.
Don't Listen to Experts on Afghanistan|Masood Aziz|May 28, 2010|DAILY BEAST
But this post-partisan dream, it turns out, rested on two fallacies.
Obama Gets His Mojo Back|Peter Beinart|March 11, 2010|DAILY BEAST
The educated world repeated to itself these grotesque fallacies till it lost sight of plain and simple truths.
The Unsolved Riddle of Social Justice|Stephen Leacock

All these fallacies are perfectly transparent to these men; and they would laugh at you for putting them forward.
The History of England in Three Volumes, Vol.III.|E. Farr and E. H. Nolan
A catalogue of the varieties of apparent evidence which are not real evidence, is an enumeration of Fallacies.
A System of Logic: Ratiocinative and Inductive|John Stuart Mill
The Classification of Fallacies which will be attempted in the ensuing chapter, is founded on these considerations jointly.
A System of Logic: Ratiocinative and Inductive|John Stuart Mill
Fallacies of Induction, where the facts on which the induction proceeds are erroneous, may be termed Fallacies of Observation.
A System of Logic: Ratiocinative and Inductive|John Stuart Mill

British Dictionary definitions for fallacy

fallacy

/ (ˈfæləsɪ) /

noun plural -cies

an incorrect or misleading notion or opinion based on inaccurate facts or invalid reasoning

unsound or invalid reasoning

the tendency to mislead

logic an error in reasoning that renders an argument logically invalid

Word Origin for fallacy

C15: from Latin fallācia, from fallax deceitful, from fallere to deceive

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

Cultural definitions for fallacy

fallacy

A false or mistaken idea based on faulty knowledge or reasoning. For example, kings who have divorced their wives for failing to produce a son have held to the fallacy that a mother determines the sex of a child, when actually the father does. (See sex chromosomes.)

fallacy

OTHER WORDS FOR fallacy

Origin of fallacy

Words related to fallacy

How to use fallacy in a sentence

British Dictionary definitions for fallacy

Word Origin for fallacy

Cultural definitions for fallacy