Barque: n. a sailing ship with from three to five masts, all of them square-rigged except the after mast, which is fore-and-aft rigged.
Before the mast: adv. as a common sailor. Originated because the sailors live in the forecastle, forward of the foremast.
Brigantine: n. two-masted sailing ship, square-rigged on the foremast and having a fore and aft mainsail with square main topsails.
Hermaphrodite brig: n. a two-masted vessel with her foremast fully square-rigged and her mainmast fore-and-aft rigged.
Keelson: n. a longitudinal beam connected to the keel of a ship to strengthen her.
Pink Stern: n. a vessel with a very narrow stern.
Privateer: n. a privately-owned warship commissioned to prey on the commercial shipping or warships of an enemy nation.
Rider: n. an interior rib occasionally fixed in a ship’s hold, reaching from the keelson to the beams of the lower deck, to strengthen her frame.
Schooner: n. a vessel with two or more masts, usually of equal height and gaff-rigged for greater sail area and ability to point. (i.e. steer upwind into a breeze)
Smack: n. a small sailing vessels, commonly rigged as sloops, used chiefly in the coasting and fishing trade.
Tonnage: n. the number of tons of water a ship displaces when she’s afloat.
Yellow metalled: a. covered with a layer of brass, probably with a high zinc alloy.
For many more nautical terms, visit the Wikipedia glossary site.