a. The brother of one's mother or father.
b. The husband of a sibling of one's mother or father.
2. Used as a form of address for an older man, especially by children.
3. A kindly counselor.
4. Slang A pawnbroker.
5. Uncle Uncle Sam.
cry/say uncle Informal
To indicate a willingness to give up a fight or surrender: tickled my brother until he cried uncle.
[Middle English, from Anglo-Norman, from Latin avunculus, maternal uncle; see awo- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 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.