- The definition of countersue is when someone is suing you and you turn around and sue them.
When your neighbor sues you for trespassing and you sue your neighbor for encroaching on your land, this is an example of a time when you countersue.
countersue 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.
countersue definition by American Heritage Dictionary
transitive verb coun·ter·sued, coun·ter·su·ing, coun·ter·sues Law
To bring proceedings against (a plaintiff) in direct opposition to a suit brought against onself.
- counˈter·suitˌ noun