jack

noun

1. A coarse medieval coat of defence, especially one made of leather.
2. A name applied to a hypothetical or typical man.
3. A man, a fellow; a typical man; men in general.
4. A sailor.
5. A policeman or detective; (Australia) a military policeman.
6. A manual laborer.
7. A lumberjack.
8. A sepoy.
9. A device for turning a spit; a smokejack or roasting jack.
10. 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.
11. a tool used in manual production of glass objects (like bottles or wine glasses).
12. A support for wood being sawn; a sawhorse or sawbuck.
13. A device used to hold a boot by the heel, to assist in removing the boot.
14. 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.
15. 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.
16. A wedge for separating rocks rent by blasting.
17. A grating device used to separate and guide the threads in a warping machine; a heck-box.
18. A machine for twisting the sliver as it leaves a carding machine, in the preparation of yarn.
19. A switch for a jack plug, a jackknife switch; (more generally) a socket used to connect a device to a circuit, network etc.
20. A pitcher or other vessel for holding liquid, especially alcoholic drink; a black-jack.