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

Observational studies have found that higher calcium intakes were associated with a higher incidence of prostate cancer. —Melissa Nieves, Verywell Health, 27 Mar. 2025

Monday was World Tuberculosis Day and, as usual, Americans had reason to celebrate, with incidence rates that are among the best anywhere, according to the World Health Organization. —Paul Sisson, Mercury News, 25 Mar. 2025

Since 2014, however, the incidence rate has increased by 3 percent per year. —Paul Smaglik, Discover Magazine, 24 Mar. 2025

In Fort Worth, residents of neighborhoods such as Como, Las Vegas Trail, Historic Southside, Seminary, the Stop 6 area, and Diamond Hill, have a higher incidence of asthma, based on data from CDC Places. —Kamal Morgan, Fort Worth Star-Telegram, 21 Mar. 2025

Word History

First Known Use

1626, in the meaning defined at sense 2a

Phrases Containing incidence

• angle of incidence

Rhymes for incidence

• coincidence

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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