infest

verb

in·​fest in-ˈfest 

infested; infesting; infests

transitive verb

1

: to spread or swarm in or over in a troublesome manner

shark-infested waters

2

: to live in or on as a parasite

infestant

in-ˈfe-stənt 

noun

infestation

ˌin-ˌfe-ˈstā-shən 

noun

infester

in-ˈfe-stər 

noun

Synonyms of infest

• plague
• infect
• overrun
• crawl
• overwhelm

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

Despite those efforts, New World screwworm infested thousands of animals in Panama and Mexico, and in June, the US Department of Agriculture confirmed the first US cases in years. — Jen Christensen, CNN Money, 7 Sep. 2026

Inspectors noted a rice bucket was heavily infested with roaches. — Lillie Davidson, Fort Worth Star-Telegram, 1 Sep. 2026

If the wood that’s exposed after the bark sheds is rotting or infested with pests, the tree may not be in good health. — Karen Brewer Grossman, Southern Living, 22 Aug. 2026

The inspection followed a hunger strike by detainees, who in a letter, complained about rotten or worm-infested food, medical neglect, and being coerced into signing deportation orders. — Vanessa Romo, NPR, 20 Aug. 2026

Word History

Etymology

French infester, from Latin infestare, from infestus hostile

First Known Use

1602, in the meaning defined at sense 1

Rhymes for infest

• abreast
• accessed
• addressed
• appressed
• armrest
• arrest
• assessed
• attest
• backrest
• behest
• bequest
• caressed

Kids Definition

infest

verb

in·​fest in-ˈfest 

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

ˌin-ˌfes-ˈtā-shən 

noun

Medical Definition

infest

transitive verb

in·​fest in-ˈfest 

: to live in or on as a parasite

the flea that infests cats

horses infested with worms

compare infect