(n.) A bar of iron athwart ships at a topgallant masthead, to support a royal mast, and give spread to the royal shrouds; -- called also jack crosstree.
(n.) A coarse and cheap mediaeval coat of defense, esp. one made of leather.
(n.) A compact, portable machine for planing metal.
(n.) A device to pull off boots.
(n.) A drinking measure holding half a pint; also, one holding a quarter of a pint.
(n.) A familiar nickname of, or substitute for, John.
(n.) A flag, containing only the union, without the fly, usually hoisted on a jack staff at the bowsprit cap; -- called also union jack. The American jack is a small blue flag, with a star for each State.
(n.) A grating to separate and guide the threads; a heck box.
(n.) A hood or other device placed over a chimney or vent pipe, to prevent a back draught.
(n.) A large tree, the Artocarpus integrifolia, common in the East Indies, closely allied to the breadfruit, from which it differs in having its leaves entire. The fruit is of great size, weighing from thirty to forty pounds, and through its soft fibrous matter are scattered the seeds, which are roasted and eaten. The wood is of a yellow color, fine grain, and rather heavy, and is much used in cabinetwork. It is also used for dyeing a brilliant yellow.
(n.) A large, California rock fish (Sebastodes paucispinus); -- called also boccaccio, and merou.
(n.) A lever for depressing the sinkers which push the loops down on the needles.
(n.) A machine for slicking or pebbling leather.
(n.) A machine for twisting the sliver as it leaves the carding machine.
(n.) A machine or contrivance for turning a spit; a smoke jack, or kitchen jack.
(n.) A mechanical contrivance, an auxiliary machine, or a subordinate part of a machine, rendering convenient service, and often supplying the place of a boy or attendant who was commonly called Jack
(n.) A pitcher or can of waxed leather; -- called also black jack.
(n.) A popular colloquial name for a sailor; -- called also Jack tar, and Jack afloat.
(n.) A portable machine variously constructed, for exerting great pressure, or lifting or moving a heavy body through a small distance. It consists of a lever, screw, rack and pinion, hydraulic press, or any simple combination of mechanical powers, working in a compact pedestal or support and operated by a lever, crank, capstan bar, etc. The name is often given to a jackscrew, which is a kind of jack.
(n.) A sawhorse or sawbuck.
(n.) A system of gearing driven by a horse power, for multiplying speed.
(n.) A wooden wedge for separating rocks rent by blasting.
(n.) A young pike; a pickerel.
(n.) An impertinent or silly fellow; a simpleton; a boor; a clown; also, a servant; a rustic.
(n.) In hunting, the pan or frame holding the fuel of the torch used to attract game at night; also, the light itself.
(n.) In the harpsichord, an intermediate piece communicating the action of the key to the quill; -- called also hopper.
(n.) The jurel.
(n.) The knave of a suit of playing cards.
(n.) The male of certain animals, as of the ass.
(n.) The small bowl used as a mark in the game of bowls.
(n.) The wall-eyed pike.
(v. i.) To hunt game at night by means of a jack. See 2d Jack, n., 4, n.
(v. t.) To move or lift, as a house, by means of a jack or jacks. See 2d Jack, n., 5.