n. A piece of wood or other substance, usually in the form of a peg or cork, used to stop a hole in a vessel; a stopple; a bung or stopper of any kind.n. A peg, wedge, or other appliance driven in, or used to stop a hole or fill a gap. , n. A wedge-pin forced between a rail and its chair on a railway.n. A spigot driven into place, as in a barrel, in contradistinction to one screwed in.n. A wooden stopper fitted in the opening of the pump on a ship's deck during a storm, to protect the water-tanks against lightning; a pump-stopper.n. A small piece of some substance, as metallic foil, used by a dentist to fill the cavity of a decayed tooth.n. A branch pipe from a watermain, leading to a point where a hose can be conveniently attached, and closed by a cap or plug; a fire-plug.n. In die-sinking, a cylindrical piece of soft steel the end of which is fitted to a matrix.n. A flat oblong cake of pressed tobacco.n. A man's silk or dress hat; a plug-hat.n. A worn, damaged, unfashionable, or otherwise injured article, which, by reason of its defects, has become undesirable, unsalable, or in a condition rendering it difficult to sell without a large reduction of its price, as a shelf-worn book, or an old horse worn down by hard work. Also old plug.n. A short, thick-set person.n. A workman who has served no regular apprenticeship.n. A sort of fishing-boat.n. Same as plug-rodTo stop with a plug; make tight by stopping a hole: as, to plug a decayed tooth; to plug a wound with lint.To hit with a ball or bullet: as, to plug a buck with a rifle.To cut out a plug from: said of watermelons when a tapering plug is cut out to see if the fruit is ripe, and then replaced.n. In geology, a cylindrical mass of lava, a remnant of the last eruption from a volcanic vent, which chilled in the conduit and plugged it up. See neck, 6 , and stock, 35.n. A book that does not sell at all.n. In stone-cutting, a wedge which is driven into a hole that has been drilled in a stone for the purpose of splitting it. For large pieces of stone a series of holes is drilled and a wedge or plug driven into each.n. In a steam-engine: A plug-rod; a plug-frame.n. A safety-plug; a fusible plug inserted in a boiler and made of some alloy which will melt if the temperature of the metal plate of the shell rises above a certain point by reason of low water.n. Same as peg, 7.