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
However, not all slippery slope arguments are fallacious.
—Mark Travers, Forbes.com, 26 Mar. 2025
That will in turn spread on social media, which often plays a disproportional role in boosting these disinformation efforts by providing nearly unlimited platforms for unfiltered content and fallacious and deceptive claims.
—Peter Suciu, Forbes, 23 Dec. 2024
Lawyers who argued for his ouster on behalf of the National Assembly said the claims by Mr. Yoon were fallacious.
—Choe Sang-Hun, New York Times, 1 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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Mark Travers, Forbes.com, 26 Mar. 2025
That will in turn spread on social media, which often plays a disproportional role in boosting these disinformation efforts by providing nearly unlimited platforms for unfiltered content and fallacious and deceptive claims.
—Peter Suciu, Forbes, 23 Dec. 2024
Lawyers who argued for his ouster on behalf of the National Assembly said the claims by Mr. Yoon were fallacious.
—Choe Sang-Hun, New York Times, 1 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 21 Apr. 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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