infest
Americanverb (used with object)
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to live in or overrun to an unwanted degree or in a troublesome manner, especially as predatory animals or vermin do.
I had a major problem with cockroaches infesting my kitchen.
The emerald ash borer has already infested many of the local ash trees.
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to be numerous in, as anything undesirable or troublesome.
the cares that infest the day.
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Archaic. to harass.
verb
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to inhabit or overrun in dangerously or unpleasantly large numbers
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(of parasites such as lice) to invade and live on or in (a host)
Other Word Forms
Etymology
Origin of infest
First recorded in 1375–1425; from late Middle English, from Latin infestāre “to assail, molest,” from infestus “hostile”
Explanation
The verb infest means to invade in large number, often resisting control and causing damage or hardship. Bedbugs can infest people's belongings and even their bodies, or mice may infest your kitchen if you leave the cheese out too often. Infest comes from Latin: in- means "not" and festus means "able to be seized." So infest describes something is not able to be seized, typically because it's present in such large numbers. For example, mosquitoes may infest your backyard during the summer and annoy you when you're trying to relax. Infest is usually used to describe pests, such as bugs or rodents, that overrun something in such large number that they are difficult to control.
Vocabulary lists containing infest
The Vocabulary.com Top 1000
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
An infestation occurs when fly maggots infest the living flesh of warm-blooded animals, the CDC says.
From Los Angeles Times • Sep. 17, 2025
"NWS can infest livestock, pets, wildlife, occasionally birds, and in rare cases, people."
From BBC • Aug. 25, 2025
But it's not technically possible for them to infest their own home.
From Salon • Jul. 21, 2024
It’s not all that uncommon for maggots to infest and grow in poorly healing human tissue—it’s called myiasis.
From Slate • Feb. 25, 2024
“I shall have to infest Camilla and go to the reception on her,” Louise decided.
From "Secrets at Sea" by Richard Peck
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
