A pickup, on an electric guitar, that has a pair of coils of reverse polarity connected in series - to "buck" the "hum".(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "humbucker" in a sentence
"The pickups on the bottom humbucker have pop-jet fountains in them."
"The two humbucker pickups help give it the range it needs to go from thick, weeping solos to crunchy rhythm instantly."
"This guitar sports an alder body, 24 frets with a rosewood fingerboard, an Edge Pro locking bridge system, DiMarzio pickups in a HSH configuration humbucker, single coil, humbucker, and a look that beckons to be touched."