An exclamation of defeat or a plea for mercy, especially in an informal physical contest of some kind. Uncle! Uncle! Let me out of this headlock already!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
See Uncle Sam
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.