from The Century Dictionary.
- noun In building, the lowest horizontal timber of a frame, which receives the other timbers of a wooden erection; the groundsill.
- noun In railway engin., a bed-plate used under sleepers or ties in some kinds of ground.
- noun An earth-plate or piece of metal sunk in the ground to form the connection “to earth” from a telegraph-wire. Gas- or water-mains are often made to serve as ground-plates.
Sorry, no etymologies found.
Signal and ground contacts are arranged in a ratio of 10: 1, with the ground-plate surface mounted to the board to reduce noise levels.