[1] : The Collaborative International Dictionary of English v.0.48

reef \reef\, v. t. imp.  p. p. reefed r=eft; p. pr. 
   vb. n. reefing. naut.
   to reduce the extent of as a sail by rolling or folding a
   certain portion of it and making it fast to the yard or spar.
   --totten.
   1913 webster

   to reef the paddles, to move the floats of a paddle wheel
      toward its center so that they will not dip so deeply.
      1913 webster
see also:
reefed reefing to reef the paddles 

Reef >> R Words
Reef, definition of term: Reef
reef_pag1.html

Coral Reef >> C Words
Coral Reef, definition of term: Coral Reef
coral+reef_pag1.html

Barrier Reef >> B Words
Barrier Reef, definition of term: Barrier Reef
barrier+reef_pag1.html