lagoon

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.

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

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.

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.