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

New palms should not be planted in this area as it’s infested with the fungus. — Tom MacCubbin, The Orlando Sentinel, 18 July 2026

His father’s journey home from the Trojan War delays over years, allowing gluttonous suitors to infest the family home in an attempt to become the new king of Ithaca. — Nick Romano, Entertainment Weekly, 15 July 2026

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. — Grace Toohey, Los Angeles Times, 14 July 2026

Crerand was born amid the sometimes squalid and crime-infested streets of the Gorbals area of Glasgow, to Sarah and Michael, of Irish and staunch Roman Catholic faith. — Andy Mitten, New York Times, 13 July 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