1. Having the quality of rising or floating in a fluid; tending to rise or float; as, iron is buoyant in mercury. Buoyant on the flood.
2. Bearing up, as a fluid; sustaining another body by being specifically heavier. The water under me was buoyant. (Dryden)
3. Light-hearted; vivacious; cheerful; as, a buoyant disposition; buoyant spirits. Buoy”antly.
Origin: From Buoy, & i.