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。