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!

as·sure (ə-shr)
Share:
tr.v. as·sured, as·sur·ing, as·sures
1. To inform positively, as to remove doubt: assured us that the train would be on time.
2. To cause to feel sure: a gesture that assured her of his devotion.
3. To give confidence to; reassure.
4. To make certain; ensure: "Nothing in history assures the success of our civilization" (Herbert J. Muller).
5. To make safe or secure: "We would rather forgo certain benefits in order to be assured against certain evils" (Alfred E. Smith).
6. Chiefly British To insure, as against loss.

[Middle English assuren, from Old French assurer, from Vulgar Latin *assēcūrāre, to make sure : Latin ad-, ad- + Latin sēcūrus, secure; see SECURE.]

as·sura·ble adj.
as·surer, as·suror n.

Usage Note: Assure, ensure, and insure all mean "to make secure or certain." Only assure is used with reference to a person in the sense of "to set the mind at rest": The ambassador assured the prime minister of his loyalty. Although ensure and insure are generally interchangeable, only insure is now widely used in American English in the commercial sense of "to guarantee persons or property against risk."

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.