reef

1 of 3

noun (1)

1
: a part of a sail taken in or let out in regulating size
2
: reduction in sail area by reefing

reef

2 of 3

verb

reefed; reefing; reefs

transitive verb

1
: to reduce the area of (a sail) by rolling or folding a portion
2
: to lower or bring inboard (a spar) wholly or partially

intransitive verb

: to reduce a sail by taking in a reef
reefable adjective

reef

3 of 3

noun (2)

1
a
: a chain of rocks or coral or a ridge of sand at or near the surface of water compare atoll, barrier reef
b
: a hazardous obstruction
2
: lode, vein
reefy adjective

Examples of reef in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Noun
As keystone species, parrotfish play a critical part in maintaining coral reef health by grazing on macroalgae that would otherwise suffocate coral—clearing space for reefs to regenerate. Ashlee Marie Preston, Forbes.com, 27 Mar. 2025 Studies have found that chemical sunscreens contain ingredients that are toxic to reefs, and since 2018, bans have been adopted by the state of Hawaii, the Republic of Palau, the island of Bonaire, the city of Key West, Fla., and the U.S. Virgin Islands. Jason Green, Mercury News, 27 Mar. 2025 Between May and early December, the Maldives Baa Atoll UNESCO Biosphere Reserve draws hundreds of reef manta rays to its plankton-rich currents. Lynn O'Rourke Hayes, Boston Herald, 16 Mar. 2025 Drawing inspiration from the sea caves and coastal reefs that define the region, the team of architects crafted a design that merges seamlessly with the landscape. New Atlas, 14 Mar. 2025 See All Example Sentences for reef

Word History

Etymology

Noun (1)

Middle English riff, from Old Norse rif; probably akin to Old Norse rīfa to rend — more at rive

Noun (2)

Dutch rif, from Middle Dutch, from Old Norse, literally rib; akin to Old English ribb rib — more at rib

First Known Use

Noun (1)

14th century, in the meaning defined at sense 1

Verb

1670, in the meaning defined at transitive sense 1

Noun (2)

1584, in the meaning defined at sense 1a

Time Traveler
The first known use of reef was in the 14th century

Browse Nearby Words

Cite this Entry

“Reef.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/reef. Accessed 2 Apr. 2025.

Kids Definition

reef

1 of 3 noun
1
: a part of a sail taken in or let out in regulating size
2
: the reduction in sail area made by reefing

reef

2 of 3 verb
: to reduce the area of (a sail) by rolling or folding a portion

reef

3 of 3 noun
: a chain of rocks or coral or a ridge of sand at or near the surface of water
Etymology

Noun

Middle English riff "reef of a sail"; of Norse origin

Noun

from Dutch rif "reef of rocks or sand"; of Scandinavian origin

More from Merriam-Webster on reef

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