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• reef
  reef

  noun

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

  noun

  another name for the Great Barrier Reef

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)

• reefs,
  present (3rd person singular)
• reefed,
  past participle,  past
• reefing
  present participle

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. 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 ² 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 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

Derived Forms

• unreefed
  adjective

Inflected Forms

Participles

• reefing
  present
• reefed
  past

Conjugated Forms

Present

• reef
  simple
• reefs
  simple
• have reefed
  perfect
• has reefed
  perfect
• am reefing
  progressive
• are reefing
  progressive
• is reefing
  progressive
• have been reefing
  perfect progressive
• has been reefing
  perfect progressive

Past

• reefed
  simple
• had reefed
  perfect
• was reefing
  progressive
• were reefing
  progressive
• had been reefing
  perfect progressive

Future

• will reef
  simple
• will have reefed
  perfect
• will be reefing
  progressive
• will have been reefing
  perfect progressive

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Etymology

Origin of reef¹

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

Origin of reef²

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

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Explanation

A reef is a raised area on the ocean floor that's made of rock, coral, or sand. If you are a scuba diver, head to a coral reef to check out the diverse marine life. A barrier reef is one that surrounds an island and creates a lagoon between the reef and the beach. When this type of reef attracts diverse ocean life, it can be popular with snorkelers and scuba divers. When you're sailing, a reef is a section of the sail that you can roll up when necessary — and to reef is to roll up a reef. Both meanings share an Old Norse root, rif, "ridge under the water."

Example Sentences

See Examples For:

reef Reef reefs reefed reefing

Duwai approached village elders with a proposal to protect part of their fishing grounds, originally a 30-by-40-metre area within the reef.

From Barron's ● Oct. 17, 2026

When they eventually arrive, they will have to navigate through a narrow gap created in the atoll's reef by the British in 1963 - the last time the island was inhabited.

From BBC ● Oct. 10, 2026

"You can swim for hours and hours along the reef in the lagoon, just skeleton after skeleton. It's all dead," said marine biologist Austin Bowden-Kerby, who visited last year and documented the devastation.

From Barron's ● Oct. 4, 2026

Clients snorkeled, learned about reef restoration and helped tend corals.

From The Wall Street Journal ● Sep. 28, 2026

Seldom did you see any devilfish here, for they like deep places, and the water along this part of the reef is shallow.

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

Australia is being urged to take urgent action to protect its world-famous Great Barrier Reef.

From Barron's ● Oct. 4, 2026

This year, marine heatwave forecasts indicate the Great Barrier Reef will be spared the worst of the conditions, giving coral there more time to recover.

From BBC ● Sep. 3, 2026

She just presented “Terms of Agreement” at the Santa Monica performance space Highways after starting the rehearsal process through a CalArts-run residency at the Reef in downtown L.A.

From Los Angeles Times ● Jun. 30, 2026

On Dec. 2, seven maritime militia vessels arrived at Antelope Reef in the Paracel Islands, said Ray Powell, director of a maritime transparency project at Stanford University called SeaLight.

From The Wall Street Journal ● May 15, 2026

I was even informed that my Xhosa was no longer pure and was now influenced by Zulu, one of the dominant languages in the Reef.

From "Long Walk to Freedom" by Nelson Mandela

"We likely will not be touching corals to each other on reefs," said Collins, noting the sheer size of reefs tends to preclude this option.

From Barron's ● Oct. 14, 2026

As coral reefs struggle to survive, many sharks are losing their main food source, but humans are to blame for that one.

From Salon ● Oct. 9, 2026

Viewers are taken into some of the world's least understood marine environments, ranging from coral reefs and tropical islands to the darkest depths of the ocean.

From BBC ● Oct. 7, 2026

Locals say dredging for the port already damaged coral reefs, resulting in a decline in marine life and tourist interest at a popular snorkeling site.

From The Wall Street Journal ● Oct. 3, 2026

As a doctoral student, she traveled to Bora Bora and Bimini; she waded onto reefs in a sun hat with a collecting bucket and harvested snails on three continents.

From "All the Light We Cannot See" by Anthony Doerr

Divers and many fishermen want more to be reefed; shrimpers complain that reefs prevent them from dragging nets across parts of the ocean floor.

From Economist ● Jun. 12, 2014

Currently, less than a tenth of America’s old oil and gas platforms are reefed.

From Economist ● Jun. 12, 2014

The firm has only reefed 12 of the 60 Gulf of Mexico platforms it has decommissioned.

From Economist ● Jun. 12, 2014

Pessimistic Mr. Avery, convinced that the U.S. was in for a slump any day, had kept Ward's canvas tightly reefed for the big blow.

From Time Magazine Archive

The main, still reefed, he tightened a bit to match the jib and the Frog seemed to leap ahead.

From "The Voyage Of The Frog" by Gary Paulsen

Part of that action is Patten’s realization that the sailor’s standard storm tactics—including reefing, heaving-to and lying a-hull—will not work in such an intense blow.

From The Wall Street Journal ● Dec. 8, 2025

Within five years oil firms will be reefing one offshore rig in four, predicts Quenton Dokken of the Gulf of Mexico Foundation, a conservation group.

From Economist ● Jun. 12, 2014

Four years ago the Golden State passed a law allowing reefing.

From Economist ● Jun. 12, 2014

Farther down the fleet, the crew on Carlo Falcone's 67-year-old Fife-designed yawl Mariella were busy reefing and shaking in tune with the lightning-lit 40-knot squalls, until losing the top of their mizzenmast.

From Time Magazine Archive

Already reefing from the floods, Cahokia never recovered from the earthquake.

From "1491" by Charles C. Mann

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Related Words

• atoll
• beach
• coral reef
• shoal

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