fallacious

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adjective fal·la·cious \ fə-ˈlā-shəs \

Definition of fallacious

1 :embodying a fallacy

a fallacious conclusion

a fallacious argument

2 :tending to deceive or mislead :delusive

false and fallacious hopes
—Conyers Middleton

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fallaciously

adverb

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fallaciousness

noun

See fallacious defined for English-language learners

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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 of fallacious from the Web

Facts and reason have to square off against the fanciful and the fallacious.

— jim rutenberg, New York Times, "Megyn Kelly, Alex Jones and a Fine Line Between News and Promotion," 14 June 2017
Clinton’s fallacious claims about 2016 sound comical.

— chris stirewalt, Fox News, "Hillary not the only Dem who doesn't get 2016," 2 June 2017
The thought that momentum carries over from game to game in the Stanley Cup playoffs is fallacious.

— eric stephens, Orange County Register, "Leon Draisaitl’s hat trick, five points power Oilers to Game 6 rout of Ducks," 7 May 2017
Problem is, the water ice on Pluto is mixed up with ices of methane, nitrogen, and carbon monoxide—which kind of hides the actual H2O. The image to the left shows this fallacious five o’clock shadow of water ice.

— nick stockton, WIRED, "Pluto Is Covered in Frozen Water. Lots of Frozen Water," 29 Jan. 2016

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'fallacious.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Did You Know?

Oh what a tangled web we weave / When first we practise to deceive! So wrote Sir Walter Scott in his 1808 poem Marmion. Scott’s line wasn't written with etymology in mind, but it might be applied to the history of "fallacious." That word traces back to the Latin verb fallere ("to deceive"), but it passed through a tangle of Latin and French forms before it eventually made its way into English in the early 1500s. Other descendants of "fallere" in English include "fail," "false," and "fault."