infect

verb

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

transitive verb

1
: to contaminate with a disease-producing substance or agent (such as bacteria)
2
a
: 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)
3
a
: 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
infector 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.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
In addition, raccoon feces may contain Baylisascaris roundworm eggs, which can infect humans and lead to nerve damage or blindness. Arricca Elin Sansone, Southern Living, 18 Oct. 2025 In cells infected with influenza A, FOOD and F-ApoEVs contained viral proteins and even whole virions, which are the complete, infectious viral particles that exist outside a host cell. New Atlas, 16 Oct. 2025 The turmoil created by the revolving door of owners infected the clubhouse. Jon Paul Hoornstra, MSNBC Newsweek, 16 Oct. 2025 The key questions posed in any zombie narrative – how did this start, how many are infected, how to contain it – are the identical questions that epidemiologists ask during a real infectious disease outbreak or pandemic. Tom Duszynski, The Conversation, 16 Oct. 2025 See All Example Sentences for infect

Word History

Etymology

Middle English infecten, enfecten "to inflict with disease, pollute, damage, corrupt," borrowed from Latin infectus, past participle of inficere "to dye, discolor, impregnate, taint, contaminate with disease," from in- in- entry 2 + facere "to make, bring about, perform, do" — more at fact

First Known Use

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

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

Browse Nearby Words

Cite this Entry

“Infect.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/infect. Accessed 22 Oct. 2025.

Kids Definition

infect

verb
in·​fect in-ˈfekt How to pronounce infect (audio)
1
: to contaminate with a disease-producing substance or germ
infected bedding
2
a
: to pass a germ or disease to
coughing people who infect others
b
: to enter and cause disease in
bacteria that infect wounds
c
: to become copied to
a virus has infected the computer
3
: to cause to share one's feelings
infected everyone with his enthusiasm
infector noun

Medical Definition

infect

transitive verb
in·​fect in-ˈfekt How to pronounce infect (audio)
1
: to contaminate with a disease-producing substance or agent (as bacteria)
2
a
: to communicate a pathogen or a disease to
b
of a pathogenic organism : to invade (an individual or organ) usually by penetration compare infest

More from Merriam-Webster on infect

Last Updated: - Updated example sentences
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