boil something down

Từ điển Oxford Advanced Learner 8th

▪ I. ˌboil ˈdown | ˌboil sthˈdown derived
to be reduced or to reduce sth by boiling
Main entry: ↑boil_derived
 
▪ II. ˌboil sth ˈdown (to sth) derived
to make sth, especially information, shorter by leaving out the parts that are not important
•The original speech I had written got boiled down to about ten minutes.
Main entry: ↑boil_derived