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

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Other Words from infest

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

Though not necessarily an immediate threat to people, the tick nonetheless has the potential to infest a range of species, including dogs, cats, and livestock, the department said in a statement issued Wednesday. Frank Kummer,, "Pets could be next target of exotic tick that infested N.J. farm," 26 Apr. 2018 Doping by Russian athletes infested biathlon for years. Tariq Panja, New York Times, "U.S. Biathletes Boycott Russia Event," 24 Feb. 2018 In October, it was found to have completely infested the paddock. Frank Kummer,, "Tenacious invasive tick survived winter in N.J. Experts are worried," 23 Apr. 2018 Pro tip: bed bugs hate slippery surfaces, so the tub is a great place to store your suitcase if you're worried your hotel might be infested! Amina Lake Abdelrahman, Good Housekeeping, "This Is the Most Effective Bed Bug Treatment, According to Experts," 8 Apr. 2019 Animal control officers found the third dog at another home and found that that dog, too, was flea-infested and smelled bad. Christine Dempsey,, "Southington Couple Charged With Neglecting Dogs," 10 Apr. 2018 The current outbreak likely began when people drew water from a bat-infested well, according to the India’s National Centre for Disease Control, which is leading the investigation. Emily Baumgaertner, New York Times, "Nipah Virus, Dangerous and Little Known, Spreads in India," 4 June 2018 Flights from New Jersey 'infested' with bed bugs, passengers claim. Fox News, "FOX NEWS FIRST: Mass shooting stuns Toronto, too early to determine if it's terror; Trump warns Iran," 23 July 2018 Behind that sanguine view is the fact that speculative mortgages no longer infest the housing market, one common culprit in financial meltdowns, and banks, another culprit, have plenty of loss-absorbing capital and liquidity. Greg Ip, WSJ, "How Long Can the Great Jobs Picture Continue? The Fed Thinks Indefinitely," 2 Nov. 2018

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.

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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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Statistics for infest

Last Updated

31 May 2019

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Time Traveler for infest

The first known use of infest was in 1602

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English Language Learners Definition of infest

of something harmful or unwanted : to be in or over (a place, an animal, etc.) in large numbers


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.
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

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More from Merriam-Webster on infest

Thesaurus: All synonyms and antonyms for infest

Spanish Central: Translation of infest

Nglish: Translation of infest for Spanish Speakers

Britannica English: Translation of infest for Arabic Speakers

Comments on infest

What made you want to look up infest? Please tell us where you read or heard it (including the quote, if possible).


to move with exaggerated bouncy motions

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