Jump To:

• 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.

---

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.

---

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. another name for the Great Barrier Reef

2. another name for the Witwatersrand

---

reef ² British  

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

reef ³ 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

---

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

---

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

Etymology

Origin of reef¹

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

Origin of reef²

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

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

In July, a fishing influencer almost lost his leg after being attacked by a reef shark whilst spearfishing.

From BBC ● Aug. 15, 2026

In one dramatic episode, an American ship, the Philadelphia, was grounded on a reef and captured, but in 1804, the Americans launched a successful mission to rescue her with no casualties.

From Salon ● Jul. 4, 2026

Kennedy Shoal is a well-known fishing reef in deep water.

From Barron's ● May 24, 2026

After nearly a year of sailing, the ship struck a reef in heavy storms and foundered on May 21, 1832.

From The Wall Street Journal ● May 20, 2026

I then crawled back to the edge of the reef.

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

Outposts built before Antelope Reef drew significant international attention.

From The Wall Street Journal ● May 15, 2026

Among other honors, he was nominated for a 2023 Society of Composers and Lyricists Award for his work scoring the movie “The Reef: Stalked.”

From Los Angeles Times ● May 11, 2026

The study -- conducted at the Shark Reef Marine Reserve in Fiji -- found that bull sharks do not simply mix randomly.

From Science Daily ● Mar. 17, 2026

Australia's Great Barrier Reef, for instance, saw peak heat stress increase each year between 2014 and 2017.

From Barron's ● Feb. 10, 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

Arabic texts as far back as the 15th century codified the discipline of navigation, though ship captains sailed the reefs from memory, using poems rather than maps to recall notable landmarks.

From The Wall Street Journal ● Aug. 6, 2026

Kinjo says that reefs flanking his seaside farm consist entirely of corals he cultivated, with their natural peers "no longer able to keep up with a tremendous increase in stress" in the anthropogenically polluted ocean.

From Barron's ● Jul. 29, 2026

To reach those ancient reefs, the team had to cross extensive layers of rock known as turbidites.

From Science Daily ● Jun. 26, 2026

Wildfires, floods, melting ice caps, heat waves, the bleaching of ocean reefs.

From Los Angeles Times ● Jun. 18, 2026

She loves to be among the living creatures, whether on the reefs or in her aquaria.

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

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

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

John Hocevar, its head of ocean campaigns, concedes that in some locations reefed platforms, if non-toxic, may increase marine life.

From Economist ● Jun. 12, 2014

Under reefed capital sail C. & E. I. bad a good chance to operate at a profit.

From Time Magazine Archive

There was a sailboat with rusty red sails reefed around the booms of the fore and aft masts.

From "Hole in My Life" by Jack Gantos

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

Operators are loth to estimate costs publicly, but the Tulane University Energy Institute reckons that reefing the state’s 27 platforms could save $2 billion.

From Economist ● Jun. 12, 2014

Operators typically favour reefing but it is not always economical or allowed, says David Welch of Stone Energy Corporation.

From Economist ● Jun. 12, 2014

But the science regarding the safety of artificial reefing is still being developed.

From Time Magazine Archive

Pole Star was reefing its own sails and slowing, guiding itself with the minimum acceleration so that it could come up beside them and board.

From "Ship Breaker" by Paolo Bacigalupi

Related Words

• atoll
• beach
• coral reef
• shoal