la·goon /ləˈgun/
  沼;池;礁湖
  la·goon n.  [Written also lagune.]
  1. A shallow sound, channel, pond, or lake, especially one into which the sea flows; as, the lagoons of Venice.
  2. A lake in a coral island, often occupying a large portion of its area, and usually communicating with the sea. See Atoll.
  Lagoon island, a coral island consisting of a narrow reef encircling a lagoon.
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  lagoon
       n : a body of water cut off from a larger body by a reef of sand
           or coral [syn: laguna, lagune]