Yes, deep is a Scrabble word!

Adverb

1. To a great depth; far down

2. To an advanced time

3. To a great distance

Adjective

1. Relatively deep or strong; affecting one deeply

2. Marked by depth of thinking

3. Having great spatial extension or penetration downward or inward from an outer surface or backward or laterally or outward from a center; sometimes used in combination

4. Very distant in time or space

5. Extreme

6. Having or denoting a low vocal or instrumental range

7. Strong; intense

8. Relatively thick from top to bottom

9. Extending relatively far inward

10. (of darkness) very intense

11. Large in quantity or size

12. With head or back bent low

13. Of an obscure nature

14. Difficult to penetrate; incomprehensible to one of ordinary understanding or knowledge

15. Exhibiting great cunning usually with secrecy

Noun

1. The central and most intense or profound part

2. A long steep-sided depression in the ocean floor

3. Literary term for an ocean