reef

1 of 3

noun (1)

ˈrēf 

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

ˈrē-fə-bəl 

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

ˈrē-fē 

adjective

Examples of reef in a Sentence

Recent Examples on the Web

Noun

Meanwhile, south Florida’s mangroves and reefs play an important role in reducing the effects of storm surge. —David Fischer, Los Angeles Times, 21 Apr. 2025

Glide past sea turtles, colorful reefs, and century-old shipwrecks in Tobago Cays Marine Park, one of the region's best spots for snorkeling and diving. —Carley Rojas Avila, Travel + Leisure, 19 Apr. 2025

Sub carrying tourists on reef tour sinks off Egypt's Red Sea; 6 die, dozens rescued Contributing: Marina Pitofsky and Julia Gomez, USA TODAY Greta Cross is a national trending reporter at USA TODAY. —Greta Cross, USA Today, 14 Apr. 2025

Scientists estimate 90% of the world’s tropical reefs will be gone by 2043 if the world does nothing. —Cat Cardenas, Variety, 10 Apr. 2025

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

Phrases Containing reef

• barrier reef
• coral reef
• reef knot
• whitetip reef shark

Rhymes for reef

• beef
• brief
• chief
• fief
• grief
• leaf
• lief
• reif
• seif
• sheaf
• thief
• belief

Kids Definition

reef

1 of 3 noun

ˈrēf 

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