- The definition of lifelong is something that will extend for the time that you are alive.
An example of lifelong is the relationship that you have with your children until you are dead.
lifelong 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.
lasting or not changing during one's whole life: a lifelong love
lifelong definition by American Heritage Dictionary
Continuing for a lifetime.