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to become mature; to become adult. All the children have grown up and the parents are left with a lot of debts.
to stop behaving like a child Kayo says we ought to grow up and stop complaining.Related vocabulary: come of age
Usage notes: often used as an order: Why were you guys wildly celebrating after scoring one goal? Grow up.
Etymology: based on the literal meaning of grow up (to change from being a child to being an adult)
1. Become an adult, as in Sam wants to be a policeman when he grows up. [First half of 1500s]
2. Come into existence, arise, as in Similar social problems grew up in all the big cities. [Late 1500s]
3. Become mature or sensible, as in It's time you grew up and faced the facts. This usage may also be in the form of an imperative (as in Don't bite your nails-grow up!) [Mid-1900s]
To become an adult: I want to be a teacher when I grow up.