demarcation

n.划界；限界

There is no demarcation line along the Yalu River. 鸭绿江是没有界线的。

There is no sharp demarcation between these two types. 在这两种结构之间，没有明显的分界。

If anyone oversteps the demarcation lines, execute him. 凡是越出自己营地范围，进入别人营地的，都应加以惩罚。