wait up

US /weɪt ʌp/
UK /weɪt ʌp/
"wait up" picture
1.

to wait for someone or something to arrive or catch up

:
Hey, wait up! I need to tie my shoe.
Don't go ahead, wait up for me.
2.

to stay awake, especially late at night, waiting for someone or something

:
I had to wait up for my brother to come home.
Don't wait up for me, I might be late.