垂直

1. Origins, structure, and basic meaning

• Structure: Spelling: 垂直. Reading: すいちょく. Core meaning: vertical; perpendicular.
• Basic usage: Representative examples: 板を床に対して垂直に立てた / 崖から垂直に落ちる線を地図へ引いた.

2. Common pitfalls and similar expressions

• Reference plane and direction
  • “Perpendicular” is natural for a right angle to a reference surface, while “vertical” describes an upright direction. Use に対して垂直 when stating the plane or line that provides the reference.