Two lines or plane congruent geometric figures which lie on top of each other are said to be coincident.
Coincident
See also
Coincident Lines, Congruent, Homothetic, SimilarExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Coincident." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Coincident.html