Yes, plug is a Scrabble word!

Verb

1. Fill or close tightly with or as if with a plug

2. Persist in working hard

3. Deliver a quick blow to

4. Make a plug for; praise the qualities or in order to sell or promote

5. Insert a plug into

6. Insert as a plug

Noun

1. Blockage consisting of an object designed to fill a hole tightly

2. A wad of something chewable as tobacco

3. Blatant or sensational promotion

4. Electrical device that fits into the cylinder head of an internal-combustion engine and ignites the gas by means of an electric spark

5. An electrical device with two or three pins that is inserted in a socket to make an electrical connection

6. An upright hydrant for drawing water to use in fighting a fire

7. An old or over-worked horse