wedge

A piece of material, such as metal or wood, thick at one edge and tapered to a thin edge at the other for insertion in a narrow crevice, used for splitting, tightening, securing, or levering.

Something shaped like a wedge.

A wedge-shaped formation, as in ground warfare.

Something that intrudes and causes division or disruption.

Something that forces an opening or a beginning.

An iron golf club with a very slanted face, used to lift the ball sharply upward, as from sand.

A shoe having a heel that extends across the shank to the half sole, forming a continuous undersurface.