Of or relating to the sea: marine exploration. Native to, inhabiting, or formed by the sea: marine animals. Of or relating to shipping or maritime affairs. Of or relating to sea navigation; nautical: a marine chart. See Synonyms at nautical. Of or relating to troops that serve at sea as well as on land, specifically the U.S. Marine Corps. A soldier serving on a ship or at a naval installation. A member of the U.S. Marine Corps. The mercantile or naval ships or shipping fleet of a country. The governmental department in charge of naval affairs in some nations. A painting or photograph of the sea.