- 分界线 fēnjièxiàn dividing lineline of demarcation; physical boundary marking the separation of two regions
- 边界线 biānjièxiàn boundary lineboundary line or border line between neighboring countries or regions
- 日界线 rìjièxiàn International Date LineThe imaginary line on the Earth's surface that marks the change of one calendar day to the next, roughly following the 180° meridian; also called [[国际日期变更线|國際日期變更線|guo2 ji4 ri4 qi1 bian4 geng1 xian4]].
- 国界线 guójièxiàn national bordernational boundary line
- 限界线 xiànjièxiàn boundary lineboundary line; dividing line
- 军事分界线 jūnshìfēnjièxiàn military demarcation lineMilitary demarcation line, such as the one separating North and South Korea.
- 划清界线 huàqīngjièxiàn to draw a clear lineTo clearly define a boundary or territory
- 越出界线 yuèchūjièxiàn to overstep the limitTo go beyond or exceed a prescribed limit or boundary.
- 临界线 línjièxiàn boundary linethe dividing line between two adjacent areas; border
