reef

1. N-COUNT A reef is a long line of rocks or sand, the top of which is just above or just below the surface of the sea. 礁

An unspoiled coral reef encloses the bay. 一道完好的珊瑚礁围绕着海湾。

2. N the part gathered in when sail area is reduced, as in a high wind 帆的可收缩部

3. V to reduce the area of (sail) by taking in a reef 收帆