infest

1 of 3

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

infester

2 of 3

transitive verb

obsolete

: to cause to fester

infester

3 of 3

noun

in·​fest·​er ə̇nˈfestə(r) 

plural -s

: one that infests

Synonyms of infest

Verb

• plague
• infect
• overrun
• crawl
• overwhelm

Examples of infest in a Sentence

Verb

in desperation, we called in an exterminator because the house was infested with ants

Recent Examples on the Web

Verb

If New World screwworm is identified in an animal in Colorado, state or federal officials will conduct an investigation to understand how the animal became infested. — Sarah Tomlinson, The Conversation, 24 July 2026

The canal that flows between Fort Lauderdale resident Harry Rozelle’s house and his church is so infested with bacteria that his teenage son, Cruz, was hospitalized after swimming in it three years ago. — Alex Harris, Miami Herald, 22 July 2026

Good property maintenance and natural and safe methods can get rid of chiggers and prevent them from infesting your space. — Barbara Gillette, The Spruce, 22 July 2026

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

Word History

Etymology

Verb

French infester, from Latin infestare, from infestus hostile

Transitive verb

in- entry 2 + fester (verb)

Noun

infest + -er

First Known Use

Verb

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