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 The nematodes will survive in the root nodules for long periods and will readily infest new garden areas through spreading of the compost., "Calvin Finch: It’s time for San Antonio tomato gardeners to start over with fall plants," 18 June 2020 It is most commonly carried by the black-legged or deer tick and can infest humans and pets. Kaleb A. Brown, Detroit Free Press, "Mobile app takes aim at the bane of Michigan summers — ticks and Lyme disease," 17 June 2020 This is a quick way to improvise a hammock to get off the ground in wet or bug-infested environments. Popular Science, "Fifteen survival shelters that can save your life," 28 May 2020 There are many species of round worms (nematodes) that can infest fish. Joe Genzel, Outdoor Life, "10 Common Parasites and Diseases Found in Game Fish (and What You Need to Know About Them)," 27 May 2020 Outhouses can be frigid or infested with rodents or insects. The Editors, Field & Stream, "Three Portable Toilets Engineered for Emergency Relief," 5 May 2020 John Park, president and CEO of a national food chain, was charged with violating the Food, Drug and Cosmetic Act for allowing food to be shipped from company warehouses infested with rats. Todd Haugh, The Conversation, "Coronavirus impact: Meat processing plants weigh risks of prosecution if they’re blamed for spreading infection," 27 Apr. 2020 Investigators unsuccessfully squeezed Caputo for proof that Trump’s campaign was infested with Kremlin operatives. Deroy Murdock, National Review, "A Patriot and a Professional," 17 Apr. 2020 In areas of the Illinois and Kentucky rivers that are heavily infested with Asian carp, native fish populations have declined significantly. Paul A. Smith, Milwaukee Journal Sentinel, "Catch of 51 Asian carp in Mississippi River near La Crosse is largest in Wisconsin or Minnesota waters," 13 Mar. 2020

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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Time Traveler for infest

Time Traveler

The first known use of infest was in 1602

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Statistics for infest

Last Updated

23 Jun 2020

Cite this Entry

“Infest.” Dictionary, Merriam-Webster, Accessed 12 Jul. 2020.

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How to pronounce infest (audio)

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

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