infest
Americanverb (used with object)
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infests,
present (3rd person singular)
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infested,
past participle, past
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infesting
present participle
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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
Derived Forms
Inflected Forms
Participles
Conjugated Forms
Present
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infestsimple
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infestssimple
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have infestedperfect
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has infestedperfect
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am infestingprogressive
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are infestingprogressive
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is infestingprogressive
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have been infestingperfect progressive
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has been infestingperfect progressive
Past
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infestedsimple
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had infestedperfect
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was infestingprogressive
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were infestingprogressive
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had been infestingperfect progressive
Future
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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Unit 1: Telling Details
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Christmas Carol Vocab: A Lyrical Lexicon
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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.
See Examples For:
Now, a burnt-out putrid warehouse that has devastated businesses and forced residents to remain inside their homes during a sweltering summer, as flies and giant rats infest the neighborhood.
From Los Angeles Times ● Aug. 8, 2026
On his cow-calf operation in the state’s southeastern plains, Diebel is already limiting opportunities for the pest to infest his herd.
From The Wall Street Journal ● Jun. 12, 2026
Officials added that the calf was undergoing treatment and improving, and emphasized that the worms do not infest food sources like meat, fruit or vegetables.
From Barron's ● Jun. 4, 2026
A more accurate metaphor would be credit termites — insects that infest and destroy structural timbers.
From MarketWatch ● May 20, 2026
“She might. I wouldn’t mind knowing where the lifeboat is. Besides, it didn’t take Beatrice long to infest Mrs. Cranston’s fur cape. What will she get up to next, do you suppose?”
From "Secrets at Sea" by Richard Peck
The pollution that infests those systems can include everything from silt and natural debris to asbestos, heavy metals, radioactive isotopes and other harmful contaminants released when man-made structures burn.
From New York Times ● Sep. 26, 2022
English ivy infests millions of trees across the country, killing them by choking, stealing nutrients and adding weight that can be deadly in high winds.
From Washington Post ● Apr. 29, 2022
It costs $200 to $500 per tree, and must be done as a preventive measure, Graves added, because once a beetle infests a tree, it’s too late.
From Washington Times ● Apr. 24, 2021
Here’s the key: During a séance, the vampires are confronted by their dead spirits; one infests a doll.
From Los Angeles Times ● Aug. 24, 2020
This insect infests about a third of Africa, posing a menace to human health and preventing the keeping of livestock in an area of some 4% million square miles of wooded grasslands.
From "Silent Spring" by Rachel Carson
While pregnant, Natasha says her room became infested with ants, which she repeatedly reported before eventually being moved into another room.
From BBC ● Aug. 24, 2026
Michael Schmoyer -- the associate administrator for the country's Animal and Plant Health Inspection Service and head of the NWS Directorate -- said the infested beef calf "is not a danger to the food supply."
From Barron's ● Jun. 4, 2026
“Our business is infested with idiots,” he famously warned, “who try to impress by using pretentious jargon.”
From The Wall Street Journal ● Apr. 30, 2026
In this method, pest control workers drill into infested wood, reach the termite "gallery" or hiding area, and inject insecticide directly inside.
From Science Daily ● Apr. 20, 2026
Another of Dr. Hargraves’ patients was a professional man who had his office in an old building infested by roaches.
From "Silent Spring" by Rachel Carson
Within weeks of the renovation’s completion, numerous defects were spotted, with a liner installed on the bottom of the pool peeling in various places, and algae again infesting the water.
From Slate ● Aug. 13, 2026
Plus, the $313 million injury bug infesting the NBA playoffs, Ted Turner’s day managing the Braves and Jason Gay.
From The Wall Street Journal ● May 15, 2026
Solanum elaeagnifolium -- also known as silverleaf nightshade -- can be found from south Texas to South Africa and Greece, infesting fields and soaking up valuable nutrients intended for cash crops.
From Science Daily ● Jun. 3, 2024
The wingless, pill-shaped insects feed on mammalian blood and, as indicated by their name, are notorious for infesting human dwellings.
From Salon ● Mar. 13, 2024
They just pushed themselves along the ground with their hands and arms, but that only led to tuktuk infesting their hands.
From "Lost Boy, Lost Girl" by John Bul Dau
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.
