Definition of FALLACIOUS

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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."

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

Ads that deploy fallacious reasoning and misrepresent the purpose of studies prey on the hopes and fears of patients, potentially subverting the integrity of informed consent. — Jonathan Kimmelman, STAT, "Cancer centers sell out science when they advertise clinical trials as treatment," 25 Apr. 2018 This word suggested a fallacious assumption: Poverty persisted only because of hitherto weak government resolve regarding the essence of war — marshalling material resources. — George Will, Alaska Dispatch News, "Old norms show a way out of poverty," 6 July 2017 But everyone's clinging to the fallacious belief that science just needs to be explained better and then people will change their minds. — Rebecca Onion, Slate Magazine, "The Angle: Bernie’s Pod Edition," 19 Apr. 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 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 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.