infection

noun

in·​fec·​tion in-ˈfek-shən 

1

a

: the state produced by the establishment of one or more pathogenic agents (such as bacteria, protozoans, or viruses) in or on the body of a suitable host

an infection in his foot

b

: a disease resulting from infection

contagious infections

infections of childhood

2

: an act or process of infecting something or someone

also : the establishment of a pathogen in its host after invasion

3

: an infectious agent or material contaminated with an infectious agent

… that notion that the infection was all in the air, that there was no such thing as contagion from the sick people to the sound …

—Daniel Defoe

It may not be uninteresting to add, that this case I vaccinated with infection taken from a secondary pock on the arm of her sister …

—John Redman Coxe

4

: the communication of emotions or qualities through example or contact

But immediately she resisted this intolerable fear as an infection from her husband's way of thinking.

—George Eliot

also : the emotion or quality that is communicated

… as the evening wore on, she caught the infection of their excitement …

—Thomas Hardy

Besides, I know what sort of a mind I have placed in communication with my own: I know it is one not liable to take infection …

—Charlotte Brontë

5

: the act or result of corrupting someone's morals, character, etc.

… it is at least as difficult to stay a moral infection as a physical one …

—Charles Dickens

… they could not know the origin—or the depth—of his susceptibility to the infection of power.

—Robert A. Caro

Examples of infection in a Sentence

Poor hygiene can increase the danger of infection.

The wound has so far remained free of infection.

steps you can take to decrease your computer's risk of infection

Recent Examples on the Web

Menopausal women spent years unable to get relief from the potentially deadly but often preventable effects of recurrent urinary tract infections, due to the FDA’s black box warning for estrogen products. — Theara Coleman, TheWeek, 24 Sep. 2026

Those concerns could be things like infections, poor healing, excessive swelling, shedding, scarring, problems with graft survival or growth. — Elizabeth Gulino, Allure, 23 Sep. 2026

One dose is 93% effective against preventing measles infection and two doses are 97% effective, the CDC says. — Mary Kekatos, ABC News, 23 Sep. 2026

If the patient has an infection, their serum will contain antibodies that can target the egg. — Beth Mole, ArsTechnica, 22 Sep. 2026

Word History

Etymology

Middle English infeccioun "morbid condition of a body part, disease, contamination," borrowed from Anglo-French & Late Latin; Anglo-French infeccioun, enfection, borrowed from Late Latin infectiōn-, infectiō "influence, process of dyeing, communication of disease, contamination," from Latin infec-, variant stem of inficere "to dye, discolor, taint, contaminate with disease" + -tiōn-, -tiō, suffix of verbal action — more at infect

First Known Use

14th century, in the meaning defined at sense 2

Phrases Containing infection

• breakthrough infection
• co-infection
• focal infection
• Vincent's infection
• yeast infection

Rhymes for infection

• abjection
• advection
• affection
• bijection
• bisection
• collection
• complexion
• confection
• connection
• connexion
• convection
• correction

Kids Definition

infection

noun

in·​fec·​tion in-ˈfek-shən 

1

: an act or process of infecting

2

a

: the state produced by something infectious (as a germ or parasite) living in or on a suitable host

b

: a disease resulting from infection : infectious disease

3

a

: something (as a bacterium or virus) infectious

b

: material contaminated with something infectious

Medical Definition

infection

noun

in·​fec·​tion in-ˈfek-shən 

1

a

: the state produced by the establishment of one or more pathogenic agents or microorganisms (as bacteria, viruses, protozoans, or fungi) in or on the body of a suitable host

treated a bacterial infection of the eye

b

: a disease resulting from infection : infectious disease

common infections of childhood

contagious infections

2

: an act or process of infecting something or someone

syphilis infection is chiefly venereal

also : the establishment of a pathogen in its host after invasion

3

: an infectious agent or material contaminated with an infectious agent