(anatomy) The anatomical position of the human skull, based on a plane passing through the inferior margin of the left orbit and the upper margin of each ear canal or external auditory meatus.

plural of Frankfurt plane

A two-dimensional plane (or other surface) of weakness along which a crystal or other solid will break when under stress.

(mathematics, engineering) The complex plane on which Laplace transforms are graphed; a mathematical domain where processes are viewed in the frequency domain rather than the time domain; used as a graphical analysis tool in engineering and physics.

(geology) A plane of separation between rock masses.

plural of divisional plane

plural of scaleboard plane

A plane for cutting from a board a wide shaving forming a scaleboard.

The cutting chisel of a joiner's plane.

(carpentry) A plane, convex in the direction of its length on the underside, for smoothing the concave faces of curved woodwork.