incidence

noun

in·​ci·​dence ˈin(t)-sə-dən(t)s 

-ˌden(t)s

1

a

: rate of occurrence or influence

a high incidence of crime

b

: an act or the fact or manner of falling upon or affecting : occurrence

2

a

: angle of incidence

b

: the arrival of something (such as a projectile or a ray of light) at a surface

Did you know?

The words incident, incidence, and instance may seem similar (and, in fact, incident and incidence are closely related), but they are applied in different ways. In current use, incidence usually means "rate of occurrence" and is often qualified in some way ("a high incidence of bear sightings"). Incident usually refers to a particular event, often something unusual or unpleasant ("many such incidents go unreported"). Instance suggests a particular occurrence that is offered as an example ("another instance of a simple change bringing real improvement"); it can also be synonymous with case ("many instances/cases in which the wrong form was submitted"). The plural incidences sometimes occurs in such contexts as "several recent incidences of bear sightings," but this use is often criticized as incorrect.

Examples of incidence in a Sentence

an increased incidence of diabetes

a high incidence of criminal behavior

Recent Examples on the Web

On his first day back in the White House, Donald Trump revoked two Biden-era executive orders that had increased the incidence of fraud in Obamacare Exchanges — on top of the other burdens that government health-care programs already impose on taxpayers. —Michael F. Cannon, National Review, 6 Feb. 2025

The agency has offered findings on the mental health effects of the pandemic on health care providers and new guidelines extending the recommendation for pneumococcal vaccines, and has warned of an increase in the incidence of tularemia, a rare infectious disease, in the United States. —Teddy Rosenbluth, New York Times, 23 Jan. 2025

Compared to male rats that didn’t consume any dye, male rats that ate the most had a significantly higher incidence of tumors — both malignant and benign — as well as abnormal cell growth in the thyroid. —Karen Kaplan, Los Angeles Times, 15 Jan. 2025

Critics of these advanced innovations have argued that these chatbots hamper our ability to truly empathize with others, while they have been infamously linked to tragic incidences encouraging violence to self or others, especially in vulnerable young people. —Dr. Tal Patalon, Md, Llb, Forbes, 21 Dec. 2024

Word History

First Known Use

1626, in the meaning defined at sense 2a

Phrases Containing incidence

• angle of incidence

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Kids Definition

incidence

noun

in·​ci·​dence ˈin(t)-səd-ən(t)s 

-sə-ˌden(t)s

1

: angle of incidence

2

: rate of occurrence

a high incidence of illness

Medical Definition

incidence

noun

in·​ci·​dence ˈin(t)-səd-ən(t)s, -sə-ˌden(t)s 

1

a

: angle of incidence

b

: the arrival of something (as a ray of light) at a surface

2

a

: an act or the fact or manner of occurring or affecting

diseases of domestic incidence

—Science

b

: rate of occurrence or influence

especially : the rate of occurrence of new cases of a particular disease in a population being studied compare prevalence