PILOT (3)

Pi″lot, n. 1. 1. (Aëronautics) One who flies, or is qualified to fly, a balloon, an airship, or a flying machine.
2. 2. (Mach.) A short plug at the end of a counterbore to guide the tool. Pilots are sometimes made interchangeable.
3. 3. (Mining) The heading or excavation of relatively small dimensions, first made in the driving of a larger tunnel.