reef
1. reef \'re-f\ n [ME riff, fr. ON rif] 1: a part of a sail taken in or let out in regulating size 2: reduction in sail area by reefing 2. reef vt 1: to reduce the area of (a sail) by rolling or folding a portion 2: to lower or bring inboard (a spar) wholly or partially : to reduce a sail by taking in a reef 3. reef n [D rif, prob. of Scand origin; akin to ON rif reef of a sail] 1a: a chain of rocks or ridge of sand at or near the surface of water 1b: a hazardous obstruction 2: VEIN, LODE