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die-off

American  
[dahy-awf, -of] / ˈdaɪˌɔf, -ˌɒf /

noun

  1. a sudden, natural perishing of large numbers of a species, population, or community.

die-off Scientific  
/ dī′ôf′ /

  1. A sudden, severe decline in a population or community of organisms as a result of natural causes. Local die-offs can be caused by such factors as an unusual or extreme weather pattern, an outbreak of disease, or toxic algal blooms in a body of water. Widespread or global die-offs in which a species or group of species becomes extinct are generally associated with rapid climate change or other large-scale environmental dislocations.

die off Idioms  

  1. Perish one by one, as in A celibate community, the Shakers are dying off. [Late 1600s]

Etymology

Origin of die-off

First recorded in 1935–40; noun use of verb phrase die off

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

In 2015, the antelope suffered a mass die-off and it was feared that the Ice Age survivors would become extinct.

From BBC • Mar. 24, 2026

"Reports from elsewhere suggest that the 2022-2023 die-off in the Canary Islands was another step in a broader marine pandemic, with serious consequences for these key reef grazers," concluded Cano.

From Science Daily • Dec. 12, 2025

Earlier this year, scientists warned that bird flu had sparked the worst die-off on record for southern elephant seals when it spread among a population on Argentina's coast in 2023.

From Barron's • Nov. 13, 2025

He’s talking about the failure to recognize the consequences of climate change manifesting in the surrounding wetlands’ die-off.

From Salon • Jul. 25, 2025

Even a year after treatment, a spring die-off of songbirds occurred and much good nesting territory lay silent and unoccupied.

From "Silent Spring" by Rachel Carson

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.