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!

boom 1 (bm)
Share:
v. boomed, boom·ing, booms
v.intr.
1. To make a deep, resonant sound.
2. To grow, develop, or progress rapidly; flourish: Business is booming.
v.tr.
1. To utter or give forth with a deep, resonant sound: a field commander booming out orders.
2. To cause to grow or flourish; boost.
n.
1. A deep resonant sound, as of an explosion.
2. A time of economic prosperity.
3. A sudden increase, as in popularity.

[Middle English bomben, imitative of a loud noise.]

boomy adj.

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 
boom 2 (bm)
Share:
n.
1. Nautical A spar extending usually from a mast to hold the foot, clew, or tack of a sail.
2. A long pole extending upward at an angle from the mast of a derrick to support or guide objects being lifted or suspended.
3.
a. A barrier composed of a chain of floating logs, typically used to block the passage of boats or to arrest the downstream motion of logs in a log drive.
b. A floating barrier serving to catch debris or to contain an oil spill.
4. A long movable arm used to maneuver and support a microphone.
5.
a. A spar that connects the tail surfaces and the main structure of an airplane.
b. A long hollow tube attached to a tanker aircraft, through which fuel flows to another aircraft being refueled in flight.
tr.v. boomed, boom·ing, booms
To move or position using a crane: boomed the cargo onto the ship.
Idiom:
drop/lower the boom
To act suddenly and forcefully to repress a practice or reprimand an offender; crack down.

[Dutch, tree, pole, from Middle Dutch; see bheuə- in the Appendix of Indo-European roots.]
(click for a larger image)
boom2
contamination containment booms

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.