in·​ci·​dence | \ ˈin(t)-sə-dən(t)s How to pronounce incidence (audio) , -ˌden(t)s \

Definition of incidence

b : the arrival of something (such as a projectile or a ray of light) at a surface
2a : an act or the fact or manner of falling upon or affecting : occurrence
b : rate of occurrence or influence a high incidence of crime

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Did You Know?

The words incident, incidence, and instance may seem similar (and, in fact, incident and incidence are closely related), but they are not used identically. In current use, incidence usually means "rate of occurrence" and is often qualified in some way ("a high incidence of diabetes"). 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 bureaucratic bumbling"); it can also be synonymous with case ("many instances in which the wrong form was submitted"). The plural incidences sometimes occurs in such contexts as "several recent incidences of crime," 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 According to the American Cancer Society, African American women have the highest incidences of Breast Cancer, and this year, 33, 840 Black women are expected to develop the illness. Jennifer Ford, Essence, "9 Beauty Buys That Support Breast Cancer Awareness," 20 Sep. 2019 Thus, my dearest reading nook is on the subway, especially the 2 and 3 trains, but with special respect for the F train, which has the highest incidence of fellow readers. Los Angeles Times, "Reading Nook: For Rivka Galchen, subways are for reading," 12 Sep. 2019 Compared to non-vegetarians, vegetarians tend to have a lower incidence of obesity, cardiovascular disease, hypertension, and certain types of cancer. Darlene Zimmerman, Detroit Free Press, "Black Bean and Corn Enchilada Casserole: Fiber rich and vegetarian," 7 Sep. 2019 Under Lula in the last decade, that was when Brazil had the highest incidence of forest fires. Nr Staff, National Review, "Episode 162: Gaffe-Prone, but Going Strong," 30 Aug. 2019 Immune hypervigilance, however, may provide such advantages as better surveillance and culling of cancer cells, which could explain why many non-reproductive cancers have higher incidence in men. Viviane Callier,, "How gender makes a difference in disease," 30 Aug. 2019 Adults who were bullied as kids have higher incidences of depression and anxiety, poorer physical health, and may even earn less than their peers, according to one groundbreaking study. Lizz Schumer, Good Housekeeping, "It's Time to Stop Commenting on Your Coworker's Lunch," 8 Aug. 2019 The lung association used the most recent data available to calculate incidence rates, screening and treatment data. oregonlive, "Survival rates climb for lung cancer patients, report says," 14 Nov. 2019 In the incidence rate, Alabama ranks 37th in the nation. Ivana Hrynkiw |, al, "In Alabama, lung cancer patients have the greatest risk of death," 13 Nov. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'incidence.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of incidence

1626, in the meaning defined at sense 1a

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The first known use of incidence was in 1626

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Last Updated

15 Dec 2019

Cite this Entry

“Incidence.” The Dictionary, Merriam-Webster Inc., Accessed 15 December 2019.

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More Definitions for incidence


How to pronounce incidence (audio)

English Language Learners Definition of incidence

: the number of times something happens or develops : the rate at which something occurs
technical : the angle at which a ray (such as a ray of light) hits a surface


in·​ci·​dence | \ ˈin(t)-səd-ən(t)s, -sə-ˌden(t)s How to pronounce incidence (audio) \

Medical Definition of incidence

b : the arrival of something (as a ray of light) at a surface
2a : an act or the fact or manner of occurring or affecting diseases of domestic incidenceScience
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

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