in·fest | \ in-ˈfest \
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 \ noun
infestation \ˌin-ˌfe-ˈstā-shən \ noun
infester \in-ˈfe-stər \ 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

That’s why the Chagos are a perfect place to study the impact of rats—which have infested 90 percent of the globe’s island groups—on bird populations. Jason Daley, Smithsonian, "Coral Reefs Need Fewer Rats and More Bird Poo," 12 July 2018 Small hive beetles also can infest a colony, destroying the structure of the hive itself and spoiling the honey. Kevin Davenport, idahostatesman, "Why are these 250,000 bees hanging out on this sweet Downtown Boise rooftop?," 11 July 2018 The rusted silos are infested with mosquitoes; there’s no grain inside or livestock nearby., "Prisonville, Texas, Hopes to Reboot Its Economy on the Back of Trump’s Immigration Crackdown," 28 June 2018 Her children also discovered that Snipes' surgical wound had become infected and infested with insects. Jordan Rau,, "Medicare takes aim at boomerang hospitalizations of nursing home patients," 22 June 2018 Your tree, bronchi infested with crows multiplying so dense no wind or light could pass through. Hartford Courant,, "The Poems Of Aaron Caycedo-Kimura: Honoring Ones Parents," 13 June 2018 His constituency was infested with heroin addiction, alcoholism, decrepit housing (his chief concern) and, as the old plants closed down, joblessness. The Economist, "Michael Martin (Lord Martin of Springburn) died on April 29th," 3 May 2018 Instead of being housed in the relative comfort of nearby Camp Lejeune with their white counterparts, the black Marines were lodged at Montford Point Camp, a swampy construction site infested with mosquitoes. Bonnie L. Cook,, "James P. Lewis, 93, postal worker and Montford Point Marine," 27 Apr. 2018 What to do when a school is infested with vermin, when textbooks are outdated, when students can’t even read? Alia Wong, The Atlantic, "In America, Schools Aren’t Required to Teach Kids to Read and Write," 6 July 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

23 Aug 2018

Look-up Popularity

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 \
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 \

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

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alleviating pain or harshness

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