1. boundary 指地图上明确的界限,汉语一般说“边界线”,如: the boundary between France and Germany 2. border 指沿边界线延伸的地区,汉语一般说“边境”,如: the Franco-German border 3.frontier 的意思是“靠外国的边界” The soldiers guarded the frontiers of the country. Sweden has frontiers with Norway and Finland.