early 15c., from M.Fr. marin (fem. marine), from O.Fr. marin, from L. marinus (fem. marina) "of the sea," from mare (gen. maris) "sea," from PIE *mori-/*mari- "body of water, lake." Cognate with O.E. mere "sea, lake, pool, pond," from P.Gmc. *mari. Noun meaning "soldier who serves on a ship" is from 1670s, from Fr. marine, from the O.Fr. adjective.
Relating to a system of open-ocean and unprotected coastal habitats, characterized by exposure to wave action, tidal fluctuation, and ocean currents and by the absence of trees, shrubs, or emergent vegetation. Water in the marine system is at or near the full salinity of seawater. Compare lacustrine, palustrine, riverine.