A buoy is a floating marker anchored to the bottom of a body of water to show where something is or warn of danger. Sailors use buoys to navigate safely: a red buoy might mark the edge of a shipping channel, while a yellow buoy could warn that rocks lie just below the surface. Buoys come in different shapes and colors, each with its own meaning, like traffic signs for the water.

Some buoys bob quietly on the waves, while others have bells that ring or lights that flash to help sailors find them in fog or darkness. Scientists also use buoys equipped with instruments to measure ocean temperatures, wave heights, and weather conditions.

The word works as a verb too, meaning to keep something afloat or lift someone's spirits. A life jacket buoys a swimmer in the water. When your friend feels discouraged about a difficult assignment, your encouragement might buoy their confidence and help them keep trying. The adjective buoyant describes both something that floats well and a cheerful, optimistic mood that keeps bouncing back no matter what.