境きょう界かい線せん

noun

boundary line; border line

Refers to a physical or conceptual dividing line, such as between properties, regions, or abstract categories.

• この川かわが二ふたつの県けんの境きょう界かい線せんになっている。

  This river serves as the boundary line between the two prefectures.

• 境きょう界かい線せんを越こえて隣となりの土と地ちに入はいらないでください。

  Please do not cross the boundary line onto the neighboring property.