reef

UK: /ˈriːf/ US: /rif/ ,(rēf )

WordReference Random House Learner's Dictionary of American English © 2025

reef¹ /rif/   n. [countable]

1. a ridge or bank of rocks or sand, often of coral debris, at or near the surface of the water.

WordReference Random House Unabridged Dictionary of American English © 2025

reef¹  (rēf ), n. 

1. a ridge of rocks or sand, often of coral debris, at or near the surface of the water.
2. Mining a lode or vein.

• Dutch rif
• earlier riff(e) 1575–85

reef²  (rēf ), [Naut.]
n. 

1. Nautical, Naval Terms a part of a sail that is rolled and tied down to reduce the area exposed to the wind.

v.t. 
2. Nautical, Naval Terms to shorten (sail) by tying in one or more reefs.
3. Nautical, Naval Terms to reduce the length of (a topmast, a bowsprit, etc.), as by lowering, sliding inboard, or the like.
4. Nautical, Naval Terms to pull (old oakum) out of seams, as with a rave hook (often fol. by out).
• Dutch reef
• Middle English refe (noun, nominal) 1350–1400

Collins Concise English Dictionary © HarperCollins Publishers::

reef / riːf/ noun

1. a ridge of rock, sand, coral, etc, the top of which lies close to the surface of the sea
2. a vein of ore, esp one of gold-bearing quartz

Etymology: 16th Century: from Middle Dutch ref, from Old Norse rif rib¹, reef²

reef / riːf/ noun

1. the part gathered in when sail area is reduced, as in a high wind

verb

1. to reduce the area of (sail) by taking in a reef
2. (transitive) to shorten or bring inboard (a spar)

Etymology: 14th Century: from Middle Dutch rif; related to Old Norse rif reef, rib¹, German reffen to reef; see reef¹

Collins Concise English Dictionary © HarperCollins Publishers::

Reef / riːf/ noun the Reef ⇒

1. another name for the Great Barrier Reef
2. another name for the Witwatersrand