piggyback board

piggyback board

[′pig·ē‚bak ‚bȯrd]
(electronics)
A small printed circuit board that is mounted on a larger board to provide additional circuitry.

piggyback board

A small printed circuit board that plugs into another circuit board in order to enhance its capabilities. It does not plug into the motherboard, but would plug into the boards that plug into the motherboard.