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
For people accustomed to the idea that nature was eternal and unchanging, Holmes observes, the idea of extinction was profoundly troubling.
—Kathryn Schulz, New Yorker, 9 Feb. 2026
Starship launches from Starbase Musk has often spoken about his vision of colonizing other worlds in our solar system to ensure humanity's survival in the event of an extinction-level even on Earth.
—Eric Lagatta, USA Today, 9 Feb. 2026
Honeybees have never been in danger of extinction.
—Dana Milbank, Washington Post, 6 Feb. 2026
The International Union for Conservation of Nature (IUCN) Red List contains over 48,000 species threatened with extinction among 172,600 species assessed.
—Tom Page, CNN Money, 4 Feb. 2026
See All Example Sentences for extinction
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Kathryn Schulz, New Yorker, 9 Feb. 2026
Starship launches from Starbase Musk has often spoken about his vision of colonizing other worlds in our solar system to ensure humanity's survival in the event of an extinction-level even on Earth.
—Eric Lagatta, USA Today, 9 Feb. 2026
Honeybees have never been in danger of extinction.
—Dana Milbank, Washington Post, 6 Feb. 2026
The International Union for Conservation of Nature (IUCN) Red List contains over 48,000 species threatened with extinction among 172,600 species assessed.
—Tom Page, CNN Money, 4 Feb. 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 15 Feb. 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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