lagoon

[luh-goon] /ləˈgun/
noun
1.
an area of shallow water separated from the sea by low sandy dunes.
Compare laguna.
2.
Also, lagune. any small, pondlike body of water, especially one connected with a larger body of water.
3.
an artificial pool for storage and treatment of polluted or excessively hot sewage, industrial waste, etc.
Origin of lagoon
1605-15; earlier laguna (singular), lagune (plural) < Italian < Latin lacūna (singular), lacūnae (plural) ditch, pool, akin to lacus basin, lake1; see lacuna
Related forms
lagoonal, adjective
Examples from the web for lagoon
British Dictionary definitions for lagoon

lagoon

/ləˈɡuːn/
noun
1.
a body of water cut off from the open sea by coral reefs or sand bars
2.
any small body of water, esp one adjoining a larger one
Also (rare) lagune
Word Origin
C17: from Italian laguna, from Latin lacūna pool; see lacuna
Word Origin and History for lagoon
n.

1670s, lagune, earlier laguna (1610s), from French lagune or directly from Italian laguna "pond, lake," from Latin lacuna "pond, hole," from lacus "pond" (see lake (n.1)). Originally in reference to the region of Venice; applied 1769 (by Capt. Cook) to the lake-like stretch of water enclosed in a South Seas atoll. Also cf. -oon.

lagoon in Science
lagoon
  (lə-gn')   

  1. A shallow body of salt water close to the sea but separated from it by a narrow strip of land, such as a barrier island, or by a coral reef.

  2. A shallow pond or lake close to a larger lake or river but separated from it by a barrier such as a levee.