extinction
noun
ex·tinc·tion
ik-ˈstiŋ(k)-shən 
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
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
Benjamin Plackett 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.
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
The fossil record suggests these massive creatures disappeared during the sweeping extinctions that marked the end of the Pleistocene.
—Hanna Wickes, Fort Worth Star-Telegram, 17 Mar. 2026
The series once again finds itself in a prescient position with the industry on the precipice of an extinction-level event, and Valerie once again rises to the occasion with a message worth hearing, delivered with a smile that’s improbably radiant.
—Ben Travers, IndieWire, 17 Mar. 2026
The Dodo and Other Projects in the Pipeline The dodo, a flightless bird driven to extinction by human activity roughly 400 years ago, is one of Colossal’s active projects.
—Hanna Wickes, Charlotte Observer, 16 Mar. 2026
All beasts are subject to sudden and violent extinction at the hands of other beasts.
—Jessica Gelt, Los Angeles Times, 13 Mar. 2026
See All Example Sentences for extinction
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Hanna Wickes, Fort Worth Star-Telegram, 17 Mar. 2026
The series once again finds itself in a prescient position with the industry on the precipice of an extinction-level event, and Valerie once again rises to the occasion with a message worth hearing, delivered with a smile that’s improbably radiant.
—Ben Travers, IndieWire, 17 Mar. 2026
The Dodo and Other Projects in the Pipeline The dodo, a flightless bird driven to extinction by human activity roughly 400 years ago, is one of Colossal’s active projects.
—Hanna Wickes, Charlotte Observer, 16 Mar. 2026
All beasts are subject to sudden and violent extinction at the hands of other beasts.
—Jessica Gelt, Los Angeles Times, 13 Mar. 2026
See All Example Sentences for extinction
Cite this Entry
“Extinction.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/extinction. Accessed 19 Mar. 2026.
Copy CitationKids Definition
extinction
noun
ex·tinc·tion
ik-ˈstiŋ(k)-shən
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
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
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