REEF

noun a large vein of auriferous quartz;

— so called in australia. hence, any body of rock yielding valuable ore.

2. reef ·noun a chain or range of rocks lying at or near the surface of the water. ·see coral reefs, under coral.

3. reef ·vt to reduce the extent of (as a sail) by roiling or folding a certain portion of it and making it fast to the yard or spar.

4. reef ·vt that part of a sail which is taken in or let out by means of the reef points, in order to adapt the size of the sail to the force of the wind.