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.
-
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
-
(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
-
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
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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:
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
NWS can infest people and pets as well, but the risk to humans is low, and human cases of screwworm are rare.
From BBC ● Jun. 4, 2026
A more accurate metaphor would be credit termites — insects that infest and destroy structural timbers.
From MarketWatch ● May 20, 2026
Skilled at creeping under floorboards and behind skirting boards, they infest houses.
From "Fantastic Beasts and Where to Find Them" by J.K. Rowling
“Practical Magic 2” is the story of an ancient recurring curse: the lack of originality that infests Hollywood like the frosty cloud that seeps into Regan’s bedroom in “The Exorcist.”
From The Wall Street Journal ● Sep. 10, 2026
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
The kids may be top students, but the culture of money and luxury brands that infests the campuses leaves them feeling like lower-class outcasts rather than full members of the community.
From Washington Post ● Mar. 1, 2019
The pest currently infests forests from Colorado to Vermont and Georgia.
From Washington Times ● Jan. 18, 2017
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
The same invasive insect was found to have infested grapevines sold at select Northern California Costco warehouses earlier this year, also triggering a major response to try to limit the insect’s impact.
From Los Angeles Times ● Jul. 14, 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
"In areas where these termites are common, it's just a matter of time before homes are infested, so this study is a good initial step toward alternative strategies for controlling them."
From Science Daily ● May 9, 2026
It was infested with so many scorpions that anyone entering the bathroom at night carried a flashlight.
From The Wall Street Journal ● Apr. 24, 2026
Her caribou had been so infested with the larvae of nose flies it had not been able to eat.
From "Julie of the Wolves" by Jean Craighead George
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
One expert testified that the bed bugs had been infesting the mattress for at least three months before Moore discovered them.
From Los Angeles Times ● Jul. 26, 2023
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
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