na-adjective, noun which may take the genitive case particle 'no', noun
vertical; perpendicular; upright
Technical term used in physics, engineering, and mathematics to describe a direction exactly aligned with gravity or a line perpendicular to a horizontal plane. More precise than 垂直, which can mean perpendicular to any surface.
この柱は鉛直に立っている。
This pillar stands perfectly vertical.
鉛直方向の力を計算してください。
Please calculate the force in the vertical direction.