plug

n. [ Akin to D. plug, G. pflock, Dan. plök, plug, Sw. plugg; cf. W. ploc. ] 1. Any piece of wood, metal, or other substance used to stop or fill a hole; a stopple. [ 1913 Webster ]

2. A flat oblong cake of pressed tobacco. [ U. S. ] [ 1913 Webster ]

3. A high, tapering silk hat. [ Slang, U.S. ] [ 1913 Webster ]

4. A worthless horse. [ Slang, U.S. ] [ 1913 Webster ]

5. (Building) A block of wood let into a wall, to afford a hold for nails. [ 1913 Webster ]

6. An act of plugging{ 6 }; a brief mention for the sake of publicity or advertisement, especially during a public event not specifically intended for advertising purposes; as, he put in a plug for his favorite charity. [ PJC ]

Breech plug (Gun.), in breech-loading guns, the metal plug or cylinder which closes the aperture in the breech, through which the gun is loaded. --
Fire plug, a street hydrant to which hose may be attached. [ U. S. ] --
Hawse plug (Naut.), a plug to stop a hawse hole. --
Plug and feather. (Stone Working) See Feather, n., 7. --
Plug centerbit, a centerbit ending in a small cylinder instead of a point, so as to follow and enlarge a hole previously made, or to form a counterbore around it. --
Plug rod (Steam Eng.) , a rod attached to the beam for working the valves, as in the Cornish engine. --
Plug valve (Mech.), a tapering valve, which turns in a case like the plug of a faucet. [ 1913 Webster ]