Yes, captain is a Scrabble word!

Verb

1. Be the captain of a sports team

Noun

1. An officer holding a rank below a major but above a lieutenant

2. The naval officer in command of a military ship

3. A policeman in charge of a precinct

4. An officer who is licensed to command a merchant ship

5. The leader of a group of people

6. The pilot in charge of an airship

7. A dining-room attendant who is in charge of the waiters and the seating of customers