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counterexample

American

[koun-ter-ig-zam-puhl, -zahm-] / ˈkaʊn tər ɪgˌzæm pəl, -ˌzɑm- /

noun

an example that refutes an assertion or claim.

counterexample British

/ ˈkaʊntərɪɡˌzɑːmpəl /

noun

an example or fact that is inconsistent with a hypothesis and may be used in argument against it

"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

Etymology

Origin of counterexample

First recorded in 1955–60; counter- + example

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

counterexample

One of the key reasons the Jacobian conjecture is so intriguing is that, in theory, it should be easy to find a counterexample.

From Science Daily ● Aug. 6, 2026

The next head-spinning result arrived when Anthropic’s Fable model found a counterexample to the Jacobian conjecture, a famously treacherous problem that had defied mathematicians for 87 years.

From The Wall Street Journal ● Aug. 1, 2026

Argentina offers a solid counterexample: Voters reward discipline.

From Barron's ● Nov. 4, 2025

Chamberlain, Vanderbilt University geologist Steven Goodbred, and colleagues stumbled on a counterexample by chance.

From Science Magazine ● Jun. 17, 2024

Show, by means of a counterexample, that the converse is false.

From "The Curious Incident of the Dog in the Night-Time" by Mark Haddon

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023