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

Studies have shown that only one out of every eight incidences of gunfire is reported to authorities. Dan Rosenbaum, Ars Technica, "All hail the AI overlord: Smart cities and the AI Internet of Things," 7 Dec. 2018 Some of the incidences were anonymously reported to Newport administration. Jayda Evans, The Seattle Times, "A battle for respect, then in the trenches: For Newport’s Jenna Martz, football is feminism," 26 Oct. 2018 However, investigators predict the actual number of incidences is likely much higher due to the tendency of such cases to go unreported. Carson Kessler, Fortune, "In-Flight Sexual Assaults Are Increasing 'At an Alarming Rate'," 21 June 2018 Almost 30 percent of all incidences reported in the survey involved alcohol and 21 percent involved over-the-counter drugs. Shari Rudavsky, Indianapolis Star, "Drugged up dogs & catatonic cats? Survey finds all too often our pets get into our meds," 7 May 2018 But as previously reported by Traveler's Rachel Rabkin Peachman, dozens of animals died flying in cargo on U.S. airlines in 2016; United has one of the highest incidences of pet deaths. Katherine Lagrave, Condé Nast Traveler, "Dog Dies After United Flight Attendant Insists Carrier Be Put in Overhead Bin," 15 Mar. 2018 The incidence of banker malfeasance and theft is high, and someone has to represent all those employees who get caught. James Atlas, Town & Country, "The Year of the Celebrity Super Lawyer," 3 Dec. 2018 Concurrently, research finds that depression in youth is also on the rise, with the incidence of major depressive episodes in people ages 12 to 17 increasing from 8.7 percent in 2005 to 11.3 percent in 2014, particularly among girls. Brian Resnick, Vox, "America’s teens are extremely stressed out about school shootings," 31 Oct. 2018 And then, interestingly, aspirin also reduces the incidences of fever in the post-operative period. Sandy Bauers,, "How high-tech genomics - and simple aspirin - could make your joint replacement better," 17 May 2018

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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Last Updated

10 Mar 2019

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The first known use of incidence was in 1626

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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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More from Merriam-Webster on incidence

Spanish Central: Translation of incidence

Nglish: Translation of incidence for Spanish Speakers

Britannica English: Translation of incidence for Arabic Speakers

Comments on incidence

What made you want to look up incidence? Please tell us where you read or heard it (including the quote, if possible).


the range of authority or knowledge

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