a.

1. 有浮力的；能浮起的
   Wood is buoyant on water.

   木头能浮于水面。

2. 趋于上升的；上涨的
   a buoyant stock market

   行情看涨的股票市场

3. 心情愉快的；活泼的
   Children are usually more buoyant than adults.

   孩子往往比成年人快乐。

adj.

1. able or tending to keep afloat.
2. cheerful and optimistic.
3. (of an economy or market) engaged in much activity.