What is "humbucker"

n. (context music English) A pickup, on an electric guitar, that has a pair of coils of reverse polarity connected in series - to "buck" the "hum".

A humbucking pickup, humbucker, or double coil, is a type of electric guitar pickup that uses two coils to "buck the hum" (or cancel out the interference) picked up by coil pickups. Most pickups use magnets to produce a magnetic field around the strings, and induce an electrical current in the coils as the strings vibrate (a notable exception is the piezoelectric pickup). Humbuckers work by pairing a coil with the north poles of its magnets oriented "up", (toward the strings) with a coil which has the south pole of its magnets oriented up. By connecting the coils together out of phase, the interference is significantly reduced via phase cancellation. The coils can be connected in series or in parallel. In addition to electric guitar pickups, humbucking coils are sometimes used to cancel hum in dynamic microphones.

Hum is caused by the alternating magnetic fields created by transformers and power supplies inside electrical equipment using alternating current. While playing a guitar without humbuckers, a musician would hear a hum through the pickups during quiet sections of music. Sources of studio and stage hum include high-power amps, processors, mixers, motors, power lines, and other equipment. Compared to unshielded single coil pickups, humbuckers dramatically reduce hum.