stop

1. In a music box or other spring-wound instrument, a mechanical device (such as the Geneva Stop) which locks the winding shaft after a certain number of turns, preventing overwinding. 2. In an organ or other instrument with pipes, a register for controlling one or more ranks of pipes. In a pipe organ or reed organ manually-operated stops are located above or beside the keyboard and are called draw-stops, draw-knobs, or stop tabs.