青あお線せん

noun

blue line

General term for a blue-colored line, used in maps, diagrams, or as a visual marker.

• 地ち図ず上じょうの青あお線せんは川かわを表あらわしている。

  The blue line on the map represents a river.

noun

blue-line area; illegal prostitution zone

Historical term for areas marked with a blue line on police maps where illegal prostitution occurred, roughly 1940s to 1956. Abbreviation of 青線地帯.

See also: 青線地帯

• 戦せん後ごの東とう京きょうには青あお線せんと呼よばれる地ち域いきがいくつか存そん在ざいした。

  In postwar Tokyo, there were several areas called blue-line districts.

noun

non-legal public waterway; blue-line waterway

A waterway shown by a blue line on cadastral maps that is not legally recognized as a public waterway; sometimes the waterway no longer physically exists.

• この土と地ちの公こう図ずには青あお線せんで表ひょう示じされた水すい路ろがある。

  On the cadastral map of this land, there is a waterway shown by a blue line.