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

Jurors heard testimony from three of Alsheikh’s victims who said they were packed into small, filthy, cold, wet cells that were infested with insects and other vermin. — Brittny Mejia, Los Angeles Times, 19 Sep. 2026

For bare soil or areas heavily infested with persistent weeds, apply a 2- to 3-inch-thick layer of organic mulch directly over the bare soil. — Manjot Kaur Sidhu, The Conversation, 10 Sep. 2026

The man takes on work as a trauma cleaner in hopes of facing his past, but the job soon begins to infest and unravel his mental state. — Matt Grobar, Deadline, 9 Sep. 2026

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

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