a ridge of rocks, sand, or coral at or near the surface of watera vein of ore; a lode [Dutch rif, prob of Scandinavian origin]
a part of a sail taken in or let out to regulate the area exposed to the wind [Middle English riff from Old Norse rif]
to reduce the area of (a sail) exposed to the wind by rolling up or taking in a portionto shorten (a spar)