1.
boundary line, border, dividing line
A line that marks the limit or edge between two areas, territories, or categories. Used both literally for physical borders and figuratively for abstract distinctions.
境界線を引く。
To draw a boundary line.
仕事と私生活の境界線があいまいになっている。
The boundary between work and private life has become blurred.
この川が二つの県の境界線になっていて、向こう岸はもう隣の県だ。
This river serves as the boundary between the two prefectures, and the other bank is already the next prefecture.
USAGE:
Used for both physical boundaries (between countries, properties, regions) and abstract ones (between categories, concepts, roles). The figurative use is very common in modern Japanese.
COMMON COLLOCATIONS:
- 境界線を引く: to draw a boundary line
- 境界線を越える: to cross a boundary
- 境界線があいまい: the boundary is unclear
- 境界線上: on the borderline