Yes, cork is a Scrabble word!

Verb

1. Close a bottle with a cork

2. Stuff with cork

Noun

1. Outer bark of the cork oak; used for stoppers for bottles etc.

2. (botany) outer tissue of bark; a protective layer of dead cells

3. A port city in southern Ireland

4. The plug in the mouth of a bottle (especially a wine bottle)

5. A small float usually made of cork; attached to a fishing line