This is the 5842nd most frequent Chinese word.
国境
National border.
In this sentence, '国境线' refers to the concept of a national border as a geographical concept.
国境线是一道重要的地理界线。
The border line is an important geographical boundary.
Here, '国境' denotes the functional area near the boundary where immigration processes take place.
移民检查站通常设在国境附近。
Immigration checkpoints are usually located near the border.
In this context, '国境' represents the act of crossing from one country's territory into another's.