A man. • A name applied to a hypothetical or typical man. • A man, a fellow; a typical man; men in general. • A sailor. • A policeman or detective; (Australia) a military policeman. • A manual laborer. • A lumberjack. • A sepoy. • A mechanical device or utensil used for lifting. • A device for turning a spit; a smokejack or roasting jack. • Each of a series of blocks in a harpsichord or the earlier virginal, communicating the action of the key to the quill; sometime also, a hopper in a modern piano. • a tool used in manual production of glass objects (like bottles or wine glasses). • A support for wood being sawn; a sawhorse or sawbuck. • A device used to hold a boot by the heel, to assist in removing the boot. • A mechanical device used to raise and (temporarily) support a heavy object, now especially to lift one side of a motor vehicle when (e.g.) changing a tyre. • Any of various levers for raising or lowering the sinkers which push the loops down on the needles in a knitting machine or stocking frame. • A wedge for separating rocks rent by blasting. • A grating device used to separate and guide the threads in a warping machine; a heck-box. • A machine for twisting the sliver as it leaves a carding machine, in the preparation of yarn. • A switch for a jack plug, a jackknife switch; (more generally) a socket used to connect a device to a circuit, network etc. • A non-tool object or thing. • A pitcher or other vessel for holding liquid, especially alcoholic drink; a black-jack. • The lowest court card in a deck of standard playing cards, ranking between the 10 and queen, with an image of a knave or pageboy on it. • A counter used to represent money in a gambling establishment. • A small, typically white, ball used as the target ball in bowls; a jack-ball. • A small ship's flag used as a signal or identifying device; a small flag flown at the bow of the vessel. • A measure of liquid corresponding to a quarter of a pint. • A fake coin designed to look like a sovereign. • A jackcrosstree. • A small, six-pointed playing piece used in the game of jacks. • A torch or other light used in hunting to attract or dazzle game at night. • Money, cash. • A strong alcoholic liquor, especially home-distilled or illicit. • Nothing, not anything, jack shit. • The eleventh batsman to come to the crease in an innings. • A smooth often ovoid large gravel or small cobble in a natural water course. • A plant or animal. • A pike, especially when young. • A male ass, especially when kept for breeding. • Any of the marine fish in the family Carangidae. • A jackrabbit. • A large California rockfish, the bocaccio, Sebastes paucispinis. • Mangifera caesia, related to the mango tree. • Plant in the genus Arisaema, also known as Jack-in-the-pulpit, and capitalized Jack. • Spadix of a plant (also capitalized Jack). • Plant of the genus Emex, also considered synonymous to Rumex, if not then containing two species lesser jack and little jack for Emex spinosa syn. Rumex spinosus, Australian English three-corner jack and prickly jack for Emex australis syn. Rumex hypogaeus.