infest

verb

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

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
infestant noun
infestation noun
infester noun

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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
At a time when division is high and negativity seems to be infesting every corner of people’s day-to-day lives, Lake Street Dive have instead chosen to go down a path of positivity. Dave Gil De Rubio, Oc Register, 25 June 2025 These rodents can infest all aspects of a home, including the shed, garage, attic, or even lawnmowers, automobiles, and barbecue grills. Arricca Elin Sansone, Southern Living, 19 June 2025 Xenophobia has always colored this nation’s past crackdowns on immigration legal and not, but the Golden State became a noxious cauldron whose anti-immigrant fumes have infested Americans in a way not seen in a century. Gustavo Arellano, Los Angeles Times, 17 June 2025 Radishes are another cabbage relative that can be infested by problematic pests like aphids and flea beetles. Brandee Gruener, Southern Living, 15 June 2025 See All Example Sentences for infest

Word History

Etymology

French infester, from Latin infestare, from infestus hostile

First Known Use

1602, in the meaning defined at sense 1

Time Traveler
The first known use of infest was in 1602

Browse Nearby Words

Cite this Entry

“Infest.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/infest. Accessed 4 Jul. 2025.

Kids Definition

infest

verb
in·​fest in-ˈfest How to pronounce infest (audio)
1
: to spread or swarm in or over in a troublesome manner
a neighborhood infested with crime
shark-infested waters
2
: to live in or on as a parasite
horses infested with worms
infestation noun

Medical Definition

infest

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

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!