boo 1 (b)
n. pl. boos
1. A sound uttered to show contempt, scorn, or disapproval.
2. Informal Any sound or word: You never said boo to me about overtime.
Used to express contempt, scorn, or disapproval or to frighten or surprise another.
v. booed, boo·ing, boos
To utter a boo.
To express contempt, scorn, or disapproval of by booing: booed the singer off the stage.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. 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:
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.