submarine

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Nautical A vessel that is capable of operating submerged.
• noun A submarine sandwich.
• noun Baseball A pitch that is thrown with a low sidearm or underhand motion.
• adjective Beneath the surface of the water; undersea.
• adjective Thrown with or characterized by a low sidearm or underhand motion.
• intransitive verb To attack by submarine, especially with torpedoes.
• intransitive verb Sports To knock down with a blow to the legs.
• intransitive verb Baseball To pitch (a ball) with a low sidearm or underhand motion.
• intransitive verb To slide, drive, or be thrown under something.
• intransitive verb To ride in or serve as a crew member of a submarine.

from The Century Dictionary.

• noun A vessel designed to navigate either entirely under water or on the surface, with a crew contained within it and with its own motive power; specifically, a submarine torpedo-boat.
• Situated or living under or in the sea, either at the bottom or below the surface; below the surface of the sea: as, submarine plants; a submarine telegraph.
• Occurring or carried on below the surface of the sea: as, submarine explorations; designed for use under the sea: as, submarine armor.
• A submarine plant.

from the GNU version of the Collaborative International Dictionary of English.

• noun Nav. A submarine boat; a ship that can travel under the surface of the water. Most such ships are ships of war, as part of a navy, but submarines are also used for oceanic research. Also called sub and (from the German U-Boot) U-boat.
• noun colloq. A stowaway on a seagoing vessel.
• noun A submarine sandwich.
• adjective Being, acting, or growing, under water in the sea.
• adjective 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.
• adjective See Telegraph cable, under Telegraph.
• adjective See Torpedo, 2 (a).
• noun A submarine plant or animal.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Under water.
• adjective Hidden or undisclosed.
• noun A boat that can go underwater.
• noun A kind of sandwich made in a long loaf of bread.
• noun baseball Pitch delivered with an underhand motion.
• noun Any submarine plant or animal.
• noun informal A stowaway on a seagoing vessel.
• verb To operate or serve on a submarine
• verb To torpedo; to destroy with a sudden sneak attack

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb control a submarine
• verb throw with an underhand motion
• verb move forward or under in a sliding motion
• noun a large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States
• noun a submersible warship usually armed with torpedoes
• adjective beneath the surface of the sea
• verb attack by submarine
• verb bring down with a blow to the legs