normal line; normal vector
Mathematics term for a line or vector perpendicular to a given curve, surface, or plane. Often used in contexts like 法線ベクトル (normal vector) or 法線方向 (normal direction).
See also: 法線ベクトル (ほうせんベクトル)
Find the normal line of the curve.
The normal vector is perpendicular to the tangent plane.
Compound of 法 (norm, law) and 線 (line), reflecting the mathematical concept of a perpendicular line. The exact historical derivation is uncertain; the term is a modern technical coinage.