in·​fest | \ in-ˈfest How to pronounce infest (audio) \
infested; infesting; infests

Definition of infest

transitive verb

1 : to spread or swarm in or over in a troublesome manner a slum infested with crime shark-infested waters
2 : to live in or on as a parasite

Other Words from infest

infestant \ in-​ˈfe-​stənt How to pronounce infest (audio) \ noun
infestation \ ˌin-​ˌfe-​ˈstā-​shən How to pronounce infest (audio) \ noun
infester \ in-​ˈfe-​stər How to pronounce infest (audio) \ noun

Synonyms for infest


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Examples of infest in a Sentence

in desperation, we called in an exterminator because the house was infested with ants
Recent Examples on the Web The invasive jumping worms reproduce more quickly, grow twice as fast and can infest soils at very high densities. Sarah Bowman, The Indianapolis Star, 26 July 2022 Inspired by the government shutdown of 2013, the series was a radical shift from the sleek halls of Lockhart Gardner: a sci-fi comedy about killer bugs from outer space that infest the brains of congressmen, turning them into hyper-partisan maniacs. Emily Nussbaum, The New Yorker, 13 June 2022 Kurt Russell stars as MacReady, one of a handful of American researchers in Antarctica who encounter an alien parasite with an uncanny ability to infest and imitate its host. Randall Colburn,, 16 May 2022 Swirls of brown mud cake the lower walls of the home and tree roots infest the foundation of Brian Redfern’s evocative and foreboding set. San Diego Union-Tribune, 23 May 2022 It’s this ability to infest areas without large groups that make these invasive jumping worms so terrifying to the local environment. Joshua Hawkins, BGR, 5 Apr. 2022 But then scammers started to infest that market, offering fake codes and scamming players out of their money, leading some unsavvy players to think that Riot had cheated them. Kyle Orland, Ars Technica, 24 Mar. 2022 Those of us who infest cinemas may remember asking ourselves that uncomfortable question for the first time. The New Yorker, 25 Feb. 2022 What should gardeners do about the aphids and bugs that infest milkweed stems and blooms? Calvin Finch, San Antonio Express-News, 17 Sep. 2021 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'infest.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of infest

1602, in the meaning defined at sense 1

History and Etymology for infest

French infester, from Latin infestare, from infestus hostile

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Last Updated

30 Jul 2022

Cite this Entry

“Infest.” Dictionary, Merriam-Webster, Accessed 26 Sep. 2022.

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More Definitions for infest


in·​fest | \ in-ˈfest How to pronounce infest (audio) \
infested; infesting

Kids Definition of infest

: to spread or swarm in or over in a harmful manner Termites infested the tree.


transitive verb
in·​fest | \ in-ˈfest How to pronounce infest (audio) \

Medical Definition of infest

: to live in or on as a parasite the flea that infests cats horses infested with worms — compare infect

More from Merriam-Webster on infest

Nglish: Translation of infest for Spanish Speakers

Britannica English: Translation of infest for Arabic Speakers


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