frontier

边界、国界、边境

They were stopped for questioning at the frontier between the two countries.

他们在两国边界被拦下来盘查。

边疆、边地

Life on the frontier was harsh, and settlers relied on each other.

边疆的生活十分艰苦，垦荒者只能互相扶持。

前沿、新领域、尖端常用复数

Gene editing has opened up new frontiers in medicine.

基因编辑为医学开拓了新的前沿领域。

边境的、边疆的

The museum recreates a frontier town from the nineteenth century.

这座博物馆重现了十九世纪的边疆小镇。