A ridge of jagged rock, coral, or sand just above or below the surface of the sea. The ship narrowly avoided crashing into the coral reef.
A part of a sail that can be rolled or folded up in order to reduce the area exposed to the wind. The sailors took in a reef to manage the strong winds during the storm.
(Mining, chiefly Australia and South Africa) A long, narrow vein of rock, especially one containing gold or other minerals. Prospectors flocked to the region after a rich gold reef was discovered.