reef
noun
a ridge of rocks or sand, often of coral debris, at or near the surface of the water.
Jump To:
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
-
another name for the Great Barrier Reef
-
another name for the Witwatersrand
reef
2
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
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
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Physical Geography - Middle School
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Physical Geography - High School
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
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:
Clients snorkeled, learned about reef restoration and helped tend corals.
From The Wall Street Journal ● Sep. 28, 2026
Researchers observed eight different types of coral, along with eight fish species using the reef for shelter and feeding.
From Science Daily ● Sep. 15, 2026
While regular mining continues in parts, there are also hundreds of abandoned shafts along the main gold reef.
From Barron's ● Sep. 1, 2026
Environmental experts say the spill threatens wildlife, protected ecosystems and fishing communities around Qeshm, which is home to mangrove forests, nearby coral reef habitats and nesting sites for critically endangered Hawksbill turtles.
From BBC ● Aug. 14, 2026
As I gazed up at its sheer cliffs, tops disappearing in a reef of ghostly clouds, the idea that this was a magical place didn’t seem so ridiculous.
From "Miss Peregrine's Home for Peculiar Children" by Ransom Riggs
Australia is being urged to take urgent action to protect its world-famous Great Barrier Reef.
From Barron's ● Oct. 4, 2026
Vietnam has formally protested against China's construction on Antelope Reef, but only in restrained, diplomatic terms.
From BBC ● Jun. 3, 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
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
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
Bowden-Kerby urged visiting Australians to see the dead reefs for themselves.
From Barron's ● Oct. 4, 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
Scientists say additional surveys may reveal more reefs elsewhere in the surrounding area.
From Science Daily ● Sep. 15, 2026
Warily they inched their way through coral reefs to their anchorage.
From "Carry On, Mr. Bowditch" by Jean Lee Latham
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
Not one platform off California has been reefed.
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
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
For now, the evidence suggests that reefing is a rare policy.
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
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
