reef
noun
a ridge of rocks or sand, often of coral debris, at or near the surface of the water.
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reef
1 American
[reef]
/ rif /
noun
-
a ridge of rocks or sand, often of coral debris, at or near the surface of the water.
-
Mining. a lode or vein.
reef
2
American
[reef]
/ rif /
noun
verb (used with object)
-
reefs,
present (3rd person singular)
-
reefed,
past participle, past
-
reefing
present participle
-
to shorten (sail) by tying in one or more reefs.
-
to reduce the length of (a topmast, a bowsprit, etc.), as by lowering, sliding inboard, or the like.
-
to pull (old oakum) out of seams, as with a rave hook (often followed byout ).
reef
1
British
/ riːf /
noun
-
a ridge of rock, sand, coral, etc, the top of which lies close to the surface of the sea
-
a ridge- or mound-like structure built by sedentary calcareous organisms (esp corals) and consisting mainly of their remains
-
a vein of ore, esp one of gold-bearing quartz
Reef
2
British
/ riːf /
noun
-
another name for the Great Barrier Reef
-
another name for the Witwatersrand
reef
3
British
/ riːf /
noun
verb
-
to reduce the area of (sail) by taking in a reef
-
(tr) to shorten or bring inboard (a spar)
reef
Scientific
/ rēf /
-
A strip or ridge of rocks, sand, or coral that rises to or near the surface of a body of water.
-
See more at coral reef
Other Word Forms
Derived Forms
Inflected Forms
Participles
Conjugated Forms
Present
-
reefsimple
-
reefssimple
-
have reefedperfect
-
has reefedperfect
-
am reefingprogressive
-
are reefingprogressive
-
is reefingprogressive
-
have been reefingperfect progressive
-
has been reefingperfect progressive
Past
-
reefedsimple
-
had reefedperfect
-
was reefingprogressive
-
were reefingprogressive
-
had been reefingperfect progressive
Future
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."
Vocabulary lists containing reef
Physical Geography - Introductory
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Physical Geography - Middle School
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Physical Geography - High School
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
It had been decades since sharks last patrolled the reef off the coast of Fiji's Naidiri Village, but they returned this year following a community-led effort to protect the fishery and plant thousands of corals.
From Barron's ● Oct. 17, 2026
Coral reef recovery is a highly active area of research, with efforts ranging from using artificial nurseries to rescue reefs to finding and cultivating more heat-tolerant species.
From Barron's ● Oct. 14, 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
Hike from ridge to reef Mason’s Travel tour company leads a guided hike through Mahé’s lush Morne Seychellois National Park to secluded Anse Major beach, followed by snorkeling at Cap Ternay Marine Park.
From The Wall Street Journal ● Sep. 29, 2026
If a boat found its way in through the maze of the reef, Shell Beach would be the first thing it would see.
From "Nim’s Island" by Wendy Orr
Australia is being urged to take urgent action to protect its world-famous Great Barrier Reef.
From Barron's ● Oct. 4, 2026
Steve Irwin died on 4 September 2006, aged 44, after a stingray fatally pierced his chest while he was underwater filming a documentary at the Great Barrier Reef.
From BBC ● Sep. 4, 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
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
They wanted the chiefs to encourage their subjects to come to the Reef.
From "Long Walk to Freedom" by Nelson Mandela
Coral reef recovery is a highly active area of research, with efforts ranging from using artificial nurseries to rescue reefs to finding and cultivating more heat-tolerant species.
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
Without access to coral reefs or productive shallow waters, and with their terrestrial birds quickly exterminated, Easter Islanders turned to constructing chicken houses for intensive poultry farming.
From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond
Currently, less than a tenth of America’s old oil and gas platforms are reefed.
From Economist ● Jun. 12, 2014
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
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
At this point the Regents reefed their sails, seemed unable to proceed.
From Time Magazine Archive
We have the sails tightly reefed and tied down.
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
For now, the evidence suggests that reefing is a rare policy.
From Economist ● Jun. 12, 2014
Four years ago the Golden State passed a law allowing reefing.
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
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