( grown-ups)
Note: The spelling 'grownup' is also used. The syllable 'up' is not stressed when it is a noun.
1.
A grown-up is an adult; used by or to children.
Tell children to tell a grown-up if they’re being bullied.
= adult
N-COUNT
2.
Someone who is grown-up is physically and mentally mature and no longer depends on their parents or another adult.
I have grown-up children who’re doing well.
ADJ
3.
If you say that someone is grown-up , you mean that they behave in an adult way, often when they are in fact still a child.
She’s very grown-up.
ADJ : usu v-link ADJ
4.
Grown-up things seem suitable for or typical of adults. ( INFORMAL )
Her songs tackle grown-up subjects...
She talked in a grown-up manner.
= adult
ADJ