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.