plug 
(plŭg)
(plŭg)n.
1. An object, such as a cork or a wad of cloth, used to fill a hole tightly; a stopper.
2. A dense mass of material that obstructs a passage.
3. A usually cylindrical or conic piece cut from something larger, often as a sample.
4. Electricity
a. A fitting, commonly with two metal prongs for insertion in a fixed socket, used to connect an appliance to a power supply.
b. A spark plug.
5. A hydrant.
6.
a. A flat cake of pressed or twisted tobacco.
b. A piece of chewing tobacco.
7. Geology A mass of igneous rock filling the vent of a volcano.
8. Informal A favorable public mention of a commercial product, business, or performance, especially when broadcast.
9. Slang Something inferior, useless, or defective, especially an old, worn-out horse.
10. Slang A gunshot or bullet: a plug in the back.
11. A fishing lure having a hook or hooks.
v. plugged, plug·ging, plugs
v. tr.
1. To fill (a hole) tightly with or as if with a plug; stop up.
2. To insert (something) as a plug: plugged a cork in the bottle.
3. To insert in an appropriate place or position: plug a quarter into the parking meter; plugged the variables into the equation.
4. Slang
a. To hit with a bullet; shoot.
b. To hit with the fist; punch.
5. Informal To publicize (a product, for example) favorably, as by mentioning on a broadcast: authors who plug their latest books on TV talk shows.
v. intr.
Phrasal Verbs: 1. To become stopped up or obstructed: a gutter that plugged up with leaves.
2. Informal To move or work doggedly and persistently: “You may plug along fifty years before you get anywhere” (Saul Bellow).
plug in
1. To connect (an appliance) to an electrical outlet.
2. To function by being connected to an electrical outlet: a power drill that plugs in.
3. Slang To cause (someone) to use a computer network, the internet, or an electronic device.
4. Slang To become informed about or involved with: was eager to plug in to the campus social scene.
plug into
1. To connect or be connected in the manner of an electrical appliance: The local system is plugged into the national telephone network. This computer plugs into a data bank.
2. Slang To cause (someone) to use a computer network, the internet, or an electronic device.
3. Slang To cause to be informed about or involved with: connoisseurs who are plugged into the current art scene.
[Dutch, from Middle Dutch plugge.]
plugger n.