reef

¹ American  

[reef] / rif /

noun

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.

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reef ² American  

[reef] / rif /

noun

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

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verb (used with object)

1. to shorten (sail) by tying in one or more reefs.

2. to reduce the length of (a topmast, a bowsprit, etc.), as by lowering, sliding inboard, or the like.

3. to pull (old oakum) out of seams, as with a rave hook (often followed byout ).

reef ¹ British  

/ riːf /

noun

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

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verb

1. to reduce the area of (sail) by taking in a reef

2. (tr) to shorten or bring inboard (a spar)

reef ² British  

/ riːf /

noun

1. a ridge of rock, sand, coral, etc, the top of which lies close to the surface of the sea

2. a ridge- or mound-like structure built by sedentary calcareous organisms (esp corals) and consisting mainly of their remains

3. a vein of ore, esp one of gold-bearing quartz

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Reef ³ British  

/ riːf /

noun

1. another name for the Great Barrier Reef

2. another name for the Witwatersrand

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reef Scientific  

/ rēf /

1. A strip or ridge of rocks, sand, or coral that rises to or near the surface of a body of water.

2. See more at coral reef

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Other Word Forms

• unreefed adjective

Etymology

Origin of reef¹

1575–85; earlier riff ( e ) < Dutch rif

Origin of reef²

1350–1400; Middle English refe (noun) < Dutch reef

Example Sentences

The tide was lower than expected, so the landing craft were hung up on a reef.

From The Wall Street Journal • Mar. 4, 2026

After establishing how heat stress corresponded to reef damage at surveyed sites, the team applied satellite based heat data to estimate impacts on reefs that were not directly studied.

From Science Daily • Feb. 12, 2026

The clandestine artisanal miners, many from neighbouring countries, have become an entrenched presence in the shantytowns that ring Johannesburg and its satellite settlements along the gold reef.

From Barron's • Jan. 23, 2026

In Belfast Lough, the oysters are placed on the seabed to form a natural reef over time and potentially provide habitat for spat from the nurseries to settle on.

From BBC • Jan. 9, 2026

The water here was only a little over my waist, and I let myself down over the reef.

From "Island of the Blue Dolphins" by Scott O'Dell

Related Words

• atoll
• beach
• coral reef
• shoal