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

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.

Synonyms

• destruction
• devastation
• havoc
• loss
• demolition
• extermination

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

It was enacted the year before the Endangered Species Act, at a time when the movement to save whales from extinction was growing. —Jason Ma, Fortune, 12 Oct. 2025

Behind closed doors, network execs cursed the growing power, and seeming lack of accountability, of streamers, while many of those at Netflix, YouTube, Prime Video and their kin still saw their linear counterparts as dinosaurs nearing extinction. —Jesse Whittock, Deadline, 12 Oct. 2025

Green turtles, once on the brink of extinction, have bounced back, a new report found. —Tom Chivers, semafor.com, 12 Oct. 2025

For example, in Ecuador’s Galápagos Islands, invasive species like rats and feral cats are considered one of the main causes of extinctions, including to the islands’ famous birds. —Jessica Beaudette, The Conversation, 11 Oct. 2025

Word History

First Known Use

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

Phrases Containing extinction

• extinction coefficient
• mass extinction
• mass extinction event
• self-extinction

Rhymes for extinction

• distinction
• contradistinction
• tinction

Kids 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