bust up phrasal verb informal ( see also ↑ bust )
1 . British English if people bust up, they end their relationship or friendship SYN break up :
They bust up after six years of marriage.
⇨ ↑ bust-up (1)
2 . bust something ↔ up to prevent an illegal activity or bad situation from continuing SYN break up :
A couple of teachers stepped in to bust up the fight.
3 . bust something ↔ up American English to damage or break something:
A bunch of bikers busted up the bar.
4 . American English to start laughing a lot SYN crack up :
Elaine busted up laughing at the sight of him.