1
general::
Phrase(s): grow up
to become mature; to become adult. • All the children have grown up and the parents are left with a lot of debts.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
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]
American Heritage Idioms