[ in-fest ]
/ ɪnˈfɛst /

verb (used with object)

to live in or overrun to an unwanted degree or in a troublesome manner, especially as predatory animals or vermin do: Sharks infested the coastline.
to be numerous in, as anything undesirable or troublesome: the cares that infest the day.
Archaic. to harass.

Origin of infest

1375–1425; late Middle English < Latin infestāre to assail, molest, derivative of infestus hostile

Related forms

in·fest·er, nounre·in·fest, verb (used with object)un·in·fest·ed, adjective

Can be confused

infect infest invest Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for infest

British Dictionary definitions for infest


/ (ɪnˈfɛst) /

verb (tr)

to inhabit or overrun in dangerously or unpleasantly large numbers
(of parasites such as lice) to invade and live on or in (a host)

Derived Forms

infestation, nouninfester, noun

Word Origin for infest

C15: from Latin infestāre to molest, from infestus hostile
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for infest


[ ĭn-fĕst ]


To live as a parasite in or on tissues or organs or on the skin and its appendages.
To inhabit or overrun in numbers large enough to be harmful, threatening, or obnoxious.

Related forms

in′fes•tation n.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.