What does "surface" mean?

Additional senses

1. 2.(Geom.) A magnitude that has length and breadth without thickness; superficies; as, a plane surface; a spherical surface.
2. 3.(Fort.) That part of the side which is terminated by the flank prolonged, and the angle of the nearest bastion. Stocqueler. Caustic surface, Heating surface, etc. See under Caustic, Heating, etc. -- Surface condensation, Surface condenser. See under Condensation, and Condenser. -- Surface gauge (Mach.), an instrument consisting of a standard having a flat base and carrying an adjustable pointer, for gauging the evenness of a surface or its height, or for marking a line parallel with a surface. -- Surface grub (Zoöl.), the larva of the great yellow underwing moth (Triphoena pronuba). It is often destructive to the roots of grasses and other plants. -- Surface plate (Mach.), a plate having an accurately dressed flat surface, used as a standard of flatness by which to test other surfaces. -- Surface printing, printing from a surface in relief, as from type, in distinction from plate printing, in which the ink is contained in engraved lines.
3. 4.To give a surface to; especially, to cause to have a smooth or plain surface; to make smooth or plain.
4. 5.To work over the surface or soil of, as ground, in hunting for gold.