planar
/ˈpleɪnə/
Of or pertaining to a plane.
A planar projection of a three-dimensional object is its projection onto a plane.
Flat, two-dimensional.
(of a graph) Able to be embedded in the plane with no edges intersecting.
A complete graph with more than four nodes is never planar.
(transistor chip, semiconductor devices) Having a flat profile, not etched into a mesa.