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1. A strip or ridge of rocks, sand, or coral that rises to or near the surface of a body of water.
2. A vein of ore.
3. Chiefly Western US A long craggy ridge or rocky escarpment.
[Obsolete Dutch rif, possibly from Old Norse, ridge.]
reef 2(rēf) Nautical
A portion of a sail gathered in and secured to lessen the area exposed to the wind.
tr.v. reefed, reef·ing, reefs
1. To reduce the size of (a sail) by gathering in a part and securing it, as by lashing it to a yard.
2. To shorten (a topmast or bowsprit) by taking part of it in.
[Partly from Middle English rif (from Old Norse rif, from rīfa, to rive) and partly from Dutch and Low German reef (Low German, from Dutch), back-formation from Dutch reven, pl. of rif, reef (of a sail), from or akin to Old Norse rif.]