Two (or more) intersecting curves that are perpendicular at their intersection are said to be orthogonal.
Orthogonal Curves
See also
Orthogonal, PerpendicularExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Orthogonal Curves." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/OrthogonalCurves.html