bright-colored; a float attached by rope to the seabed to mark channels in a harbor or underwater hazards
"The captain steered carefully past the series of red and white buoys marking the narrow channel into the port."
A float moored in water to mark a location, warn of danger, or indicate a navigational channel.
"The red buoy bobbed gently at the edge of the harbor, warning sailors that the rocks lay just beyond its line."
float on the surface of water
"The small plastic buoy bobbed gently on the calm lake surface, marking where the swimmer should enter the water."
mark with a buoy
"The harbor master ordered them to place a red and white buoy at the entrance of the narrow channel to guide incoming boats safely through the fog."
To keep afloat or aloft; used with up.
"The strong wind buoyed us up as we soared above the clouds in our glider."