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 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 Silverfish are by far one of the most cursed insects that can infest your home—right next to cockroaches and centipedes. Kelly Allen, House Beautiful, 20 July 2021 The leaftier can infest all species of hydrangeas, but in the Chicago area it is most often seen this year on the popular Annabelle cultivar of smooth hydrangea (Hydrangea arborescens ‘Annabelle’) and other smooth hydrangea cultivars, Yiesla said. Beth Botts,, 26 June 2021 Without ongoing monitoring and management, privilege creep will infest a cloud infrastructure, leaving it vulnerable to accidental or intentional damage. Raj Mallempati, Forbes, 11 June 2021 Gebru and her collaborators called out this mindset, pointing to her study with Buolamwini as evidence that being lax with data could infest machine-learning systems with biases. Tom Simonite, Wired, 8 June 2021 Harrison says that because more people are at home due to the pandemic, and cooking more rather than eating out, more ants are expected to infest houses this summer. Sudiksha Kochi, USA TODAY, 2 June 2021 Cicadas are poised to infest whole swaths of American backyards this summer. Mark Kennedy, The Christian Science Monitor, 20 May 2021 Much to the frustration of Browns fans, Steelers fans are all over Northeast Ohio, and have been known to infest FirstEnergy Stadium when Pittsburgh visits. Scott Patsko, cleveland, 4 May 2021 Rockchucks have continued to infest some school grounds in Redmond. oregonlive, 15 Apr. 2021

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

30 Jul 2021

Cite this Entry

“Infest.” Dictionary, Merriam-Webster, Accessed 5 Aug. 2021.

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More Definitions for infest



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.


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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