in·​fect | \ in-ˈfekt How to pronounce infect (audio) \
infected; infecting; infects

Definition of infect

transitive verb

1 : to contaminate with a disease-producing substance or agent (such as bacteria)
2a : to communicate a pathogen or a disease to
b of a pathogenic organism : to invade (an individual or organ) usually by penetration
c of a computer virus : to become transmitted and copied to (a device, such as a computer)
3a : contaminate, corrupt the inflated writing that infects such stories
b : to work upon or seize upon so as to induce sympathy, belief, or support trying to infect their salespeople with their enthusiasm

Keep scrolling for more

Other Words from infect

infector \ in-​ˈfek-​tər How to pronounce infector (audio) \ noun

Examples of infect in a Sentence

If you're sick you should stay home to avoid infecting other people in the office. The virus has infected many people. They were unable to prevent bacteria from infecting the wound. Her enthusiasm has infected everyone. The virus has infected many computers. All the computers in the office were infected by the same virus.
See More
Recent Examples on the Web About 220 million people around the world get infected with it every year; 435,000 of them die, according to the World Health Organization. Washington Post, "Kids in Britain help test the power of soup to fight a serious disease: Malaria," 31 Dec. 2019 The virus that Augustus had been infected with was a form of feline aids. V. S. Naipaul, The New Yorker, "The Strangeness of Grief," 30 Dec. 2019 Research has shown that about 17 to 23 percent of the nation’s prison population is infected with hepatitis C — which is most often transmitted through the sharing of needles — compared to 1 percent of the general population. Anita Hassan, NBC News, "Nevada prisoners denied hepatitis C treatment sue the state," 27 Dec. 2019 However, the animal shelter said all the puppies were infected with parvo, a highly contagious virus that attacks the gastrointestinal system. Bisma Parvez, Detroit Free Press, "German shepherd puppies dumped on I-275 ramp near Monroe," 27 Dec. 2019 Criminals often offer streams of popular shows that are infected with malware aimed at pilfering personal data, the company said. Aimee Picchi, CBS News, "Scammers target credit card users with fake "Star Wars: The Rise of Skywalker" streams," 20 Dec. 2019 Since the outbreak began in August 2018, more than 3,350 people have been infected and more than 2,200 have died. Helen Branswell, STAT, "FDA approves an Ebola vaccine, long in development, for the first time," 19 Dec. 2019 UW-La Crosse emailed students this week saying at least one student was infected and is recovering. Devi Shastri, Milwaukee Journal Sentinel, "Health officials warn college students: Wash your hands, stop adenovirus.," 6 Dec. 2019 Yu, a college undergraduate, decided to leave Poly last Thursday (Nov. 21), fearing that a burn from a tear gas shell was infected. Suzanne Sataline, Quartz, "How one fighter made his escape from the worst battle of Hong Kong’s protests," 30 Nov. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'infect.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of infect

14th century, in the meaning defined at sense 2a

History and Etymology for infect

Middle English, from Latin infectus, past participle of inficere, from in- + facere to make, do — more at do

Keep scrolling for more

Learn More about infect

Time Traveler for infect

Time Traveler

The first known use of infect was in the 14th century

See more words from the same century

Statistics for infect

Last Updated

5 Jan 2020

Cite this Entry

“Infect.” The Dictionary, Merriam-Webster Inc., Accessed 18 January 2020.

Keep scrolling for more

More Definitions for infect


How to pronounce infect (audio)

English Language Learners Definition of infect

: to cause (someone or something) to become sick or affected by disease
: to cause (someone) to feel an emotion
of an emotion : to spread to (other people)


in·​fect | \ in-ˈfekt How to pronounce infect (audio) \
infected; infecting

Kids Definition of infect

1 : to pass on or introduce a germ, illness, or disease to : to cause sickness in Don't infect me with your cold. The bacteria can infect wounds.
2 : to cause to share similar feelings Her enthusiasm infects the other players.
in·​fect | \ in-ˈfekt How to pronounce infect (audio) \

Medical Definition of infect

1 : to contaminate with a disease-producing substance or agent (as bacteria)
2a : to communicate a pathogen or a disease to
b of a pathogenic organism : to invade (an individual or organ) usually by penetration — compare infest

Keep scrolling for more

More from Merriam-Webster on infect

Thesaurus: All synonyms and antonyms for infect

Rhyming Dictionary: Words that rhyme with infect

Spanish Central: Translation of infect

Nglish: Translation of infect for Spanish Speakers

Britannica English: Translation of infect for Arabic Speakers

Comments on infect

What made you want to look up infect? Please tell us where you read or heard it (including the quote, if possible).


experienced by way of someone else

Get Word of the Day daily email!

Test Your Vocabulary

The Eponym Quiz

  • rubens painting
  • Which is the best synonym of bowdlerize?
Spell It

Can you spell these 10 commonly misspelled words?

Add Diction

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!