I. ˈrēf noun
Etymology: Middle English riff, from Old Norse rif; probably akin to Old Norse rīfa to rend — more at rive
Date: 14th century
1. : a part of a sail taken in or let out in regulating size
2. : reduction in sail area by reefing
II. verb
Date: 1667
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
• reef·able ˈrē-fə-bəl adjective
III. noun
Etymology: Dutch rif, from Middle Dutch, from Old Norse, literally rib; akin to Old English ribb rib — more at rib
Date: 1584
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