/ riːf; NAmE / noun , verb
■ noun
1.
a long line of rocks or sand near the surface of the sea :
a coral reef
2.
a part of a sail that can be tied or rolled up to make the sail smaller in a strong wind
■ verb
[ vn ] ( technical ) to make a sail smaller by tying or rolling up part of it
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WORD ORIGIN
noun sense 1 late 16th cent. (earlier as riff ): from Middle Low German and Middle Dutch rif , ref , from Old Norse rif , literally rib, used in the same sense.
noun sense 2 and verb Middle English : from Middle Dutch reef , rif , from Old Norse rif , literally rib, used in the same sense.