a ridge of rocks or sand, often of coral debris, at or near the surface of the water.
Mining. a lode or vein.
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 ).
another name for the Great Barrier Reef
another name for the Witwatersrand
to reduce the area of (sail) by taking in a reef
(tr) to shorten or bring inboard (a spar)
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
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
1575–85; earlier riff ( e ) < Dutch rif
1350–1400; Middle English refe (noun) < Dutch reef
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."
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Ornithologist Simon Hugheston-Roberts spotted the western reef heron - more commonly found in southern Europe, Africa and parts of Asia - at Y Foryd in Caernarfon at 10:00 BST on Saturday.
From BBC • Jun. 9, 2026
The 39-year-old man died from a critical head injury after he was attacked while spearfishing at Kennedy Shoal, an offshore reef, Queensland police said.
From Barron's • May 24, 2026
The “underwater city” of a barrier reef bustles with activity, with vibrantly patterned fish darting busily between corals and sea sponges.
From The Wall Street Journal • May 22, 2026
This hidden world, known as the microbiome, cannot be seen with the naked eye but plays a central role in reef health and function.
From Science Daily • May 8, 2026
One morning we left the cave and paddled out to the reef which is joined to it.
From "Island of the Blue Dolphins" by Scott O'Dell
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.
