loose end

Từ điển Oxford Advanced Learner 8th

ˌloose ˈend [loose end] BrE NAmE noun usually plural
a part of sth such as a story that has not been completely finished or explained
•The play has too many loose ends.
•There are still a few loose ends to tie up (= a few things to finish).
Idiom: ↑at a loose end
See also: ↑at loose ends