(每日一词）demarcation

Demarcation/demarkation  /ˌdiː.mɑːrˈkeɪ.ʃən/ n. （界线或规则）分界；分界线

meaning: a border or a rule that shows the limits of something or how things are divided 

1) 前缀：de-加强语气，分开

2) 词根：marc-, mark- 标记

3) 后缀：-ation 名词后缀

e.g. The river serves as the line of demarcation between the two countries. 那条河是两国的分界线。