fallacious
adjective
fal·la·cious
fə-ˈlā-shəs 
1
: embodying a fallacy
a fallacious conclusion
a fallacious argument
2
: tending to deceive or mislead : delusive
false and fallacious hopes—
Conyers Middleton
Conyers Middleton
fallaciously
adverb
fallaciousness
noun
Did you know?
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, meaning “to deceive.” (Other descendants of fallere in English include fail, false, and fault.) Fallacious arguments are a hot topic among philosophers, and some classic examples include the “ad hominem” fallacy, the “slippery slope” fallacy, and the “red herring” fallacy.
Examples of fallacious in a Sentence
it's fallacious to say that something must exist because science hasn't proven its nonexistence
consumers who harbor the fallacious belief that credit-card spending will never catch up with them
Recent Examples on the Web
There might be a bigger market for these products, and more consumers might be immune to the fallacious argument that they’re overly processed, if more people were persuaded of the ills of factory farming.
—Kenny Torrella, Vox, 7 Dec. 2018
The fallacious notion that truth is in the eye of the beholder.
—Chadd Scott, Forbes.com, 6 May 2025
Unfortunately, the Trump Administration, in its tariff policy, has embraced a framework that is basically fallacious and certain to lead to destructive policy that benefits nobody, including Americans.
—Nathan Lewis, Forbes.com, 23 Apr. 2025
However, not all slippery slope arguments are fallacious.
—Mark Travers, Forbes.com, 26 Mar. 2025
See All Example Sentences for fallacious
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Kenny Torrella, Vox, 7 Dec. 2018
The fallacious notion that truth is in the eye of the beholder.
—Chadd Scott, Forbes.com, 6 May 2025
Unfortunately, the Trump Administration, in its tariff policy, has embraced a framework that is basically fallacious and certain to lead to destructive policy that benefits nobody, including Americans.
—Nathan Lewis, Forbes.com, 23 Apr. 2025
However, not all slippery slope arguments are fallacious.
—Mark Travers, Forbes.com, 26 Mar. 2025
See All Example Sentences for fallacious
Cite this Entry
“Fallacious.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fallacious. Accessed 10 Jul. 2025.
Copy CitationKids Definition
fallacious
adjective
fal·la·cious
fə-ˈlā-shəs
1
: containing a fallacy
a fallacious argument
2
: leading in a wrong direction or into a mistaken action or belief
fallaciously
adverb
fallaciousness
noun
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