sparring partner definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
any person with whom a professional boxer spars or practices while training
sparring partner - Phrases/Idioms
An individual with whom one enjoys arguing, as in Jim's my best sparring partner. This expression alludes to boxing, where since about 1900 it has denoted the person one practices or trains with. [Mid-1900s] Also see spar with.