n.
   - a stretch of salt water separated from the sea by a low sandbank or coral reef.
 - N. Amer. & Austral./NZ a small freshwater lake near a larger lake or river.
 - an artificial pool for the treatment of effluent or to accommodate an overspill from surface drains.
 
 
  Derivative
  
  Etymology
  C17: from Ital. and Sp. laguna, from L. lacuna (see lacuna).