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



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



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



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


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

Find out more!



Check out the Dictionary Society of North America at

mo·ment (mōmənt)
1. A brief, indefinite interval of time.
a. A specific point in time, especially the present time: He is not here at the moment.
b. A point in time that is gratifying or noteworthy: Even working on a dictionary has its moments.
c. An occasion affording an opportunity: viewed the blunder as a teachable moment.
3. A particular period of importance, influence, or significance in a series of events or developments: a great moment in history; waiting for her big moment.
4. Outstanding significance or value; importance: a discovery of great moment.
5. A brief period of time that is characterized by a quality, such as excellence, suitability, or distinction: a lackluster performance that nevertheless had its moments.
6. Philosophy
a. An essential or constituent element, as of a complex idea.
b. A phase or aspect of a logically developing process.
7. Abbr. M Physics
a. The product of a quantity, such as force or mass, and its perpendicular distance from a reference point.
b. The tendency to cause rotation about a point or axis.
8. Statistics The expected value of a positive integer power of a random variable. The first moment of a random variable is the mean of its probability distribution.

[Middle English, from Old French, from Latin mōmentum, from *movimentum; see MOMENTUM.]

Synonyms: moment, instant, minute1, second1, jiffy, flash
These nouns denote a brief interval of time. A moment is an indeterminately short but significant period: I'll be with you in a moment. Instant is a period of time almost too brief to detect; it implies haste: He hesitated for just an instant. Minute is often interchangeable with moment and second with instant: The alarm will ring any minute. I'll be back in a second. Jiffy and flash are somewhat informal and usually combine with in a; in a jiffy means in a short space of time, while in a flash suggests the almost imperceptible duration of a flash of light: He went to the store but will be back in a jiffy. She finished the job in a flash. See Also Synonyms at importance.

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.