An Etymological Dictionary of Astronomy and Astrophysics

General: Slope or inclination away from the perpendicular or the horizontal; departure from a reference base.
Aeronautics: The angle measured between the tip edge of an aircraft or missile wing or other lifting surface and the plane of symmetry.
Geology: The inclination of an ore shoot, or other linear geologic structure, from the horizontal, as measured in the plane of the associated veins, faults, or foliation.

Etymology (EN): Rake, etymology unknown.

Etymology (PE): Varkeš “slope” in Gilaki dialect. It can also be literally interpreted as “departure from a surface, a side, depart away” from var, variant bar, “side, surface” + keš present stem of kešidan “to pull, drag.”