loosen up

Từ điển Oxford Advanced Learner 8th

▪ I. ˌloosen ˈup derived
to relax and stop worrying
•Come on, Jo. Loosen up.
Main entry: ↑loosen_derived
 
▪ II. ˌloosen ˈup | ˌloosen sb/sthˈup derived
to relax your muscles or parts of the body or to make them relax, before taking exercise, etc
•Dancers were loosening up before going on stage.
Main entry: ↑loosen_derived