use-icon

HOW TO USE THE DICTIONARY

To look up an entry in The American Heritage Dictionary of the English Language, use the search window above. For best results, after typing in the word, click on the “Search” button instead of using the “enter” key.

Some compound words (like bus rapid transit, dog whistle, or identity theft) don’t appear on the drop-down list when you type them in the search bar. For best results with compound words, place a quotation mark before the compound word in the search window.

guide to the dictionary

use-icon

THE USAGE PANEL

The Usage Panel is a group of nearly 200 prominent scholars, creative writers, journalists, diplomats, and others in occupations requiring mastery of language. Annual surveys have gauged the acceptability of particular usages and grammatical constructions.

The Panelists

open-icon

AMERICAN HERITAGE DICTIONARY APP

The new American Heritage Dictionary app is now available for iOS and Android.

scroll-icon

THE AMERICAN HERITAGE DICTIONARY BLOG

The articles in our blog examine new words, revised definitions, interesting images from the fifth edition, discussions of usage, and more.

100-words-icon

See word lists from the best-selling 100 Words Series!

Find out more!

open-icon

INTERESTED IN DICTIONARIES?

Check out the Dictionary Society of North America at http://www.dictionarysociety.com

in·ci·dence (ĭnsĭ-dəns)
Share:
n.
1. The rate or extent of occurrence or effect: a high incidence of malaria in the tropics.
2.
a. Usage Problem A specific event; instance or incident: fewer incidences of fraud after the regulations were enforced.
b. The action, fact, or instance of occurring: did not expect criticism and was surprised by its incidence.
3. Physics
a. The arrival of radiation, a wave, or an object at a surface.
b. Angle of incidence.

Usage Note: The singular noun incidence usually refers to the rate at which something happens, as in The city has taken measures to reduce the incidence of vandalism. In this sense, it is used in the plural only in relatively rare situations when several rates are being discussed (for example, incidences of heart disease, cancer, and stroke). However, incidence is often confused with the similar-sounding words incident and instance, which refer not to a rate but to a discrete event and are pluralized as incidents (which sounds exactly like incidence) and instances (which has an ending similar to incidences). This confusion often leads people to use incidences as a plural referring to a number of events, as in the sentence Incidences of religious intolerance are on the rise, creating tensions within many communities. In our 2014 Usage Survey, 74 percent of Panelists found this sentence unacceptable, and many Panelists remarked that incidences should be replaced with incidents or instances. The same sentence was unacceptable to 67 percent of Panelists in 2002, suggesting that there has been no increase in acceptability of this usage. A few Panelists remarked that this sentence might be acceptable if it were referring to rates of vandalism in several different places. A less ambiguous sentence (The election was marred by a few violent incidences) was rejected by 80 percent of the Panel. In this sentence, incidents is the better choice.

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
 

Indo-European & Semitic Roots Appendices

    Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

    Indo-European Roots

    Semitic Roots

    The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.