A wedge is a machine that consists of two inclined planes, giving it a thin end and thick end. A wedge is used to cut or split apart objects. wedge, in mechanics, device that tapers to a thin edge, usually made of metal or wood, and used for splitting, lifting, or tightening, as to secure a hammer head onto its handle. Along with the lever, wheel and axle, pulley, and screw, the wedge is considered one of the five simple machines.