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

Anyone who believes they may be infested with screwworm should contact their health provider. —Rachael O'Connor, MSNBC Newsweek, 31 Mar. 2026

Workers described living in overcrowded containers infested with cockroaches and bedbugs, with access to only one or two showers per year and in some cases just a single day off annually. —Efrat Lachter, FOXNews.com, 29 Mar. 2026

Allegations of betting on suicide Like other detainees, Ramsingh said that between cleanings, the rooms, restrooms and showers were often filthy and infested with insects. —Morgan Lee, Los Angeles Times, 8 Mar. 2026

Radishes are another cabbage relative that can be infested by problematic pests like aphids and flea beetles. —Brandee Gruener, Southern Living, 6 Mar. 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