1. A difficult or disagreeable responsibility or necessity; a burden or obligation.
2. Responsibility for an error or fault; blame: Each side wants to avoid the onus of having started the disagreement.
3. The burden of proof: The onus was on the defense attorney.
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.