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

Swimmer's itch is a skin rash caused by an allergic reaction to microscopic parasites that infect some birds and mammals, according to the Centers for Disease Control and Prevention. —Jalen Williams, Freep.com, 11 July 2025

Season 2 of The Last of Us finds Joel (Pedro Pascal) not only fending off humans infected with the Cordyceps virus, but other survivors seeking revenge on Joel for his past actions. —Tim Lammers, Forbes.com, 11 July 2025

Investigators said one of the patients, an 18-year-old, likely became infected about six days before his first doctor’s visit when he was bitten by fleas while walking through a prairie dog colony in Navajo County, about 103 miles east of Flagstaff, Arizona. —Saleen Martin, USA Today, 11 July 2025

As of this month, the highly contagious disease has infected nearly 175 million birds nationally, according to data from the Department of Agriculture. —Esther Sun, Mercury News, 10 July 2025

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