what's up
What's going on? What's happening? Often used as a greeting that does not require an answer. So what's up? How have you been? Well, what's up? Why are you so upset with me?
What's up?
Inf. Hello. What is happening? What's up? How're you doing? Hey, Chuck! What's up?
what’s ˈup?
(informal)
1 what’s the matter?: What’s up with him? He looks furious.
2 (especially American English) what’s new?; what’s happening?: Hey Jo, what’s up?