- The definition of grown-up is someone or something that is mature or intended for an adult.
An example of something that would be described as grown up is an R rated movie.
grown-up 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.
- that is an adult
- of, for, or like an adult
also written grownup
grown-up definition by American Heritage Dictionary
- Of, characteristic of, or intended for adults: grown-up movies; a grown-up discussion.
- Having or showing maturity in outlook, attitude, or appearance: a grown-up attitude toward work.