Meaning

• 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.