a.

1. 快的，迅速的；動作快的
   He had a rapid recovery from his illness.

   他迅速恢復了健康。

2. 陡的，險峻的
   The old man had difficulty climbing the rapid ascent.

   這位老人攀登這條陡峭的上坡路有困難。

n.

1. 急流；急湍[P][G]
   The canoeist succeeded in going over the rapids.

   操獨木舟者成功地渡過了激流。

2. 城市高速鐵路（客車）[C]

adj.

n.