infected; infecting; infects
Synonyms of infectnext

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

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.
As the outbreak stretched to a month, CDC officials expressed concerns, asking how anyone would know if a worker had been infected if they weren’t getting tested. — Nat Lash, CNN Money, 26 Oct. 2026 For that to happen, this bird flu would likely need to find an intermediate host — an animal vulnerable to viruses that infect both birds and humans. — Nat Lash, ProPublica, 23 Oct. 2026 At least 4,600 people have died and about 9,700 have been infected in Congo. — Kate Bartlett, NPR, 23 Oct. 2026 Left unchecked, the outbreak still threatens to kill livestock and wildlife, infect pets, and potentially even infect people. — Robert Kelly, Fortune, 22 Oct. 2026 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 27 Oct. 2026.

Kids Definition

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

Medical Definition

infect

transitive verb
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

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