use-icon

HOW TO USE THE DICTIONARY

Learn what the dictionary tells you about words.

Get Started Now!

Some compound words (like bus rapid transit, dog whistle, or identity theft) don’t appear on the drop-down list when you enter them into the search window. If a compound term doesn’t appear in the drop-down list, try entering the term into the search window and then hit the search button (instead of the “enter” key). Alternatively, begin searches for compound terms with a quotation mark.

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. The Panelists are surveyed annually to gauge the acceptability of particular usages and grammatical constructions.

The Panelists

puzzle-icon

NEED HELP SOLVING A CROSSWORD PUZZLE?

Go to our Crossword Puzzle Solver and type in the letters that you know, and the Solver will produce a list of possible solutions.

open-icon

INTERESTED IN DICTIONARIES?

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

open-icon

AMERICAN HERITAGE DICTIONARY APP

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

scroll-icon

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.

open-icon

OPEN DICTIONARY PROJECT

Share your ideas for new words and new meanings of old words!

Start Sharing Now!

100-words-icon

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

Find out more!

pre·vent (prĭ-vĕnt)
Share:
v. pre·vent·ed, pre·vent·ing, pre·vents
v.tr.
1. To keep from happening; avert: took steps to prevent the strike.
2. To keep (a person or thing) from doing something; impede: prevented us from winning; prevented the disease from spreading.
3. Archaic
a. To anticipate or counter in advance.
b. To come before; precede.
v.intr.
To present an obstacle: There will be a picnic if nothing prevents.

[Middle English preventen, to anticipate, from Latin praevenīre, praevent- : prae-, pre- + venīre, to come; see gwā- in the Appendix of Indo-European roots.]

pre·venta·bili·ty, pre·venti·bili·ty n.
pre·venta·ble, pre·venti·ble adj.
pre·venter n.

Synonyms: prevent, preclude, avert, obviate, forestall
These verbs mean to stop or hinder something from happening, especially by advance planning or action. Prevent implies anticipatory counteraction: "Some contemporaries believed that capitalism and the rise of an international economy would prevent war among 'civilized' states" (John Howard Morrow).
To preclude is to exclude the possibility of an event or action: "a tranquillity which ... his wife's presence would have precluded" (John Henry Newman).
Avert and obviate imply that something, such as a difficulty or necessity, has been removed or avoided: The pilot's quick thinking averted an accident. The short duration of the journey obviated the need for large food supplies. Forestall usually suggests anticipatory measures taken to counteract, neutralize, or nullify the effects of something: We installed an alarm system to forestall break-ins.

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 

This website is best viewed in Chrome, Firefox, Microsoft Edge, or Safari. Some characters in pronunciations and etymologies cannot be displayed properly in Internet Explorer.