1
: a part of a sail taken in or let out in regulating size
2
: reduction in sail area by reefing
reefed; reefing; reefs
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
: to reduce a sail by taking in a reef
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
Examples of reef in a Sentence
Recent Examples on the Web
Ashley Miznazi, Miami Herald, 20 May 2026
The itinerary includes diving and snorkeling in some of the country’s most biodiverse reefs, with frequent sightings of manta rays, reef sharks and dolphins, as well as swimming alongside whale sharks in Saleh Bay.
—Rebecca Ann Hughes, Forbes.com, 20 May 2026
Christopher Elliott, Forbes.com, 11 Jan. 2026
The rig is also designed to be reefed while preserving optimal balance between hull and appendages, meaning the yacht performs reliably in a wide range of conditions.
—Rachel Cormack, Robb Report, 30 June 2025
See All Example Sentences for reef
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Noun
That’s why scientists in Miami-Dade and the Florida Keys are asking for their help in monitoring reefs for bleaching and disease.
—Ashley Miznazi, Miami Herald, 20 May 2026
The itinerary includes diving and snorkeling in some of the country’s most biodiverse reefs, with frequent sightings of manta rays, reef sharks and dolphins, as well as swimming alongside whale sharks in Saleh Bay.
—Rebecca Ann Hughes, Forbes.com, 20 May 2026
Verb
The Halekulani's Honey & Coral Project addresses Okinawa’s crippling red soil erosion – runoff that smothers reefs – by stabilizing the soil with vegetation.
—Christopher Elliott, Forbes.com, 11 Jan. 2026
The rig is also designed to be reefed while preserving optimal balance between hull and appendages, meaning the yacht performs reliably in a wide range of conditions.
—Rachel Cormack, Robb Report, 30 June 2025
See All Example Sentences for reef
Cite this Entry
“Reef.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/reef. Accessed 21 May. 2026.
Copy CitationKids Definition
reef
1 of 3 noun1
: 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
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