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.Synonyms
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
Fish including the delta smelt, Chinook salmon and giant sturgeon are threatened with extinction.
—Bloomberg, The Mercury News, 30 Jan. 2025
This makes Stevns Klint one of the most important locations for understanding the end-Cretaceous extinction and its aftermath, offering a window into the dramatic changes in Earth's biosphere and the recovery of life following the event.
—Jonathan Granoff, Newsweek, 29 Jan. 2025
One 2017 study found that at the international level, 35 percent of countries’ national animals were threatened with extinction; however, the authors did not look at the species’ trajectories before and after they were formally recognized as national symbols.
—Maddie Bender, Smithsonian Magazine, 28 Jan. 2025
Humans have stared down extinction from pandemics, war, famine, and more during our brief time on Earth.
—Laura Baisas, Popular Science, 22 Jan. 2025
See all Example Sentences for extinction 
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Bloomberg, The Mercury News, 30 Jan. 2025
This makes Stevns Klint one of the most important locations for understanding the end-Cretaceous extinction and its aftermath, offering a window into the dramatic changes in Earth's biosphere and the recovery of life following the event.
—Jonathan Granoff, Newsweek, 29 Jan. 2025
One 2017 study found that at the international level, 35 percent of countries’ national animals were threatened with extinction; however, the authors did not look at the species’ trajectories before and after they were formally recognized as national symbols.
—Maddie Bender, Smithsonian Magazine, 28 Jan. 2025
Humans have stared down extinction from pandemics, war, famine, and more during our brief time on Earth.
—Laura Baisas, Popular Science, 22 Jan. 2025
See all Example Sentences for extinction
Dictionary Entries Near extinction
Cite this Entry
“Extinction.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/extinction. Accessed 8 Feb. 2025.
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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