A buoy (, also or ) is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with the sea wave. The word, of Old French or Middle Dutch origin, is (in British English) now most commonly pronounced (identical with boy, as in buoyant). In American English the pronunciation is closer to "boo-ee."

Buøy is an island and neighborhood (delområde) in the borough Hundvåg in Stavanger, Norway.