infect

verb

in·​fect in-ˈfekt 

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

in-ˈfek-tər 

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

With 15 cases documented so far this year, public health staff said the number of people infected with West Nile virus, half of whom live in the San Fernando Valley, outpaces the five-year average for this time period. — Matthew Rodriguez, CBS News, 21 Aug. 2026

Essentially, hackers disguise malware as ripped Blu-ray releases or other legitimate video versions of the movie, and once downloaded, users get infected. — Alan Henry, PC Magazine, 21 Aug. 2026

That’s a good thing, in the sense that even if a child is infected, the vast majority do not develop debilitating, and potentially fatal, consequences. — Eli Cahan, Rolling Stone, 21 Aug. 2026

Most humans who are infected will not experience any symptoms. — Clara Harter, Los Angeles Times, 21 Aug. 2026

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

Phrases Containing infect

• co-infect

Rhymes for infect

• affect
• aspect
• bedecked
• bisect
• collect
• connect
• correct
• deflect
• detect
• direct
• dissect
• effect

Kids Definition

infect

verb

in·​fect in-ˈfekt 

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

-ˈfek-tər 

noun

Medical Definition

infect

transitive verb

in·​fect in-ˈfekt 

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