Definition of switch plate in English:

switch plate

noun

  • 1Railways
    (chiefly US) (originally) either of the metal plates connected to or supporting a rail of a point, and attached at one end to the rails of the main track; (later) either of the metal plates reinforcing each tie at a point, and running under the rail brace and part of the rail itself (now chiefly historical).

  • 2Any of various plates on or under which a switch may be mounted; especially a flat cover for the electric wiring of an outlet box.

Origin

Mid 19th century.