being, acting, or growing, under water in the sea; as, submarine navigators; submarine plants. Submarine armor, a waterproof dress of strong material, having a helmet into which air for breathing is pumped through a tube leading from above the surface to enable a diver to remain under water. Submarine cable. See telegraph cable. Submarine mine. See torpedo, 2 .
A submarine plant or animal. 2. A ship that can travel under the surface of the water. most such ships are ships of war, part of the navy. Also called (from the german U-boot) U-boat. Nuclear submarine. A submarine powered by a nuclear reactor. Attack submarine. A submarine designed to attack other ships, including other submarines. 3. A stowaway on a seagoing vessel. [Colloq.