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

Soiled, Moldy, or Infested Items Clothing or furniture that smells of mildew, has visible stains, or has been stored in a rodent- or insect-infested environment should be discarded, never donated. —Nafeesah Allen, Better Homes & Gardens, 19 Feb. 2026

Many herbs also attract whiteflies, which will then infest your cucumbers. —Brandee Gruener, Southern Living, 16 Feb. 2026

Their eggs, laid in open wounds or on mucous membranes, would then not hatch into the flesh-eating maggots that can infest livestock, wild mammals, household pets and even humans. —John Hanna, Fortune, 10 Feb. 2026

Houseplants that are already wilting, suffering from root rot, or infested with pests shouldn't be watered with rice water, notes Harryson. —Lauren David, Martha Stewart, 10 Feb. 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