1. (n.) A chain or range of rocks lying at or near the surface of the water. See Coral.

2. (n.) A large vein of auriferous quartz; -- so called in Australia. Hence, any body of rock yielding valuable ore.

3. (v. t.) 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.

4. (v. t.) 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.

ait archipelago arrest atoll backpedal backwater bank bar bill brake breakwater cape cay check chersonese clear the decks clip the wings consider every angle continental island coral head coral heads coral island coral reef curb decelerate delay delta detain dowse sail draw rein ease off ease up flat ford forearm foreland furl guard against hand a sail head headland hedge hold back hold in check hold up holm hook impede insularity ironbound coast island island group islandology isle islet keep back key leave out nothing ledges lee shore let down let up lose ground lose momentum lose speed make sure make sure against moderate mull naze ness obstruct oceanic island overlook no possibility peninsula pitfall play safe point prepare for promontory provide a hedge provide against provide for quicksands reduce sail reef down rein in relax retard rockbound coast rocks sandbank sandbar sands sandspit set back shallow shallows shelf shoal shoal water shoals shorten sail slack off slack up slacken slow slow down slow up snug down spit spur stay take in sail take measures take precautions take steps throttle down tidal flats tongue undercurrent undertow wetlands