extinction

noun

ex·​tinc·​tion ik-ˈstiŋ(k)-shən How to pronounce extinction (audio)
plural extinctions
1
a
: the act of making extinct or causing to be extinguished
gradual extinction of the national debt
b
: the condition or fact of being extinct
also : the process of becoming extinct
attempting to save a species from extinction
… at least 17 species of the island's largest mammals, birds, and reptiles were lost in a wave of extinctions that occurred about 1,000 years ago. Pamela S. Cubberly
Now, more than 40 percent of the world's 7,000 or so languages are thought to be at risk of extinction, some with just a handful of elderly native speakers left. Benjamin Plackett
see also mass extinction
2
: the process of eliminating or reducing a conditioned (see conditioned sense 2) response by not reinforcing it
When a rat in a Skinner box presses a lever, a tone sounds momentarily, followed shortly by delivery of food. … After the animal has been conditioned in this way, the experimenter begins extinction, so that when the rat presses the lever neither the tone nor the food appears.Rita L. Atkinson et al.

Examples of extinction in a Sentence

the extinction of all life in the region the extinction of many old traditions Mass extinctions of prehistoric animals are known to have occurred.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
This discovery sheds light on the history of the species’ extinction. Real-Time News Team, Miami Herald, 3 Oct. 2025 Almost all of the largest plant and animal species on Earth were driven to extinction, including all of the non-avian dinosaurs and the last of the flying reptiles. Ethan Siegel, Big Think, 2 Oct. 2025 All part of our great age of extinctions. Robert Minhinnick, The Dial, 2 Oct. 2025 It's also believed that crabs of this species survived after a meteorite struck Earth around 66 million years ago, the infamous event that led to the extinction of dinosaurs. Scott Thompson, FOXNews.com, 2 Oct. 2025 See All Example Sentences for extinction

Word History

First Known Use

15th century, in the meaning defined at sense 1a

Time Traveler
The first known use of extinction was in the 15th century

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Cite this Entry

“Extinction.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/extinction. Accessed 10 Oct. 2025.

Kids Definition

extinction

noun
ex·​tinc·​tion ik-ˈstiŋ(k)-shən How to pronounce extinction (audio)
1
: an act of extinguishing or an instance of being extinguished
2
a
: the state of being extinct
b
: the process of becoming extinct
3
: the process of eliminating or reducing a conditioned response by not providing the stimulus with which it has become associated by conditioning

Medical Definition

extinction

noun
ex·​tinc·​tion ik-ˈstiŋ(k)-shən How to pronounce extinction (audio)
1
: the process of becoming extinct
the extinction of a species
also : the condition or fact of being extinct
2
: the process of eliminating or reducing a conditioned response by not reinforcing it

More from Merriam-Webster on extinction

Last Updated: - Updated example sentences
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