infection

noun

in·​fec·​tion in-ˈfek-shən 

1

a

: the state produced by the establishment of one or more pathogenic agents (such as a 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

Meningococcal disease, also known as meningitis, is an infection and inflammation of the fluid and membranes around the brain and spinal cord, according to the Mayo Clinic. —Vanessa Etienne, People.com, 15 May 2025

Rat bites can lead to a variety of health concerns, including infections and rat-bite fever. —Jenna Sundel, MSNBC Newsweek, 14 May 2025

Effectively treating toenail fungus (and preventing it from returning) requires an ingredient that targets the infection itself. —Lauren Paige Richeson, Health, 14 May 2025

One in 2018, linked to lettuce, caused over 200 infections across 37 states, killing five people and causing a severe kidney condition in 26. —Beth Mole, ArsTechnica, 14 May 2025

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