bad·mouth or bad-mouth (bădmouth′, -mou-=…|th=-′)
tr.v. bad·mouthed, bad·mouth·ing, bad·mouths or bad-mouthed or bad-mouth·ing or bad-mouths
To criticize or disparage, often spitefully or unfairly: "those cross-Atlantic aficionados who persistently idolize the British theater and bad-mouth Broadway" (Benedict Nightingale).
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:
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.