Buoy
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
In maritime law
A piece of wood or cork or a barrel, raft or other thing, made secure and floating upon a stream or bay, intended as a guide and warning to mariners, by marking a spot where the water is shallow or where there is a reef or other danger to navigation or to mark the ceurse of a devious channel.