A sand bar or shelf of rock lying level with, or just below, the surface of the water.

礁；暗礁；沙洲。

That part of a sail which can be drawn in and secured by small ropes, or reef points, in shortening sail.

【航】帆的卷缩部。

To reduce (a sail) by drawing in or folding up part of it.

缩蓬；卷帆。