Yes, mess is a Scrabble word!

Verb

1. Eat in a mess hall

2. Make a mess of or create disorder in

Noun

1. A state of confusion and disorderliness

2. Informal terms for a difficult situation

3. Soft semiliquid food

4. A meal eaten in a mess hall by service personnel

5. A (large) military dining room where service personnel eat or relax

6. (often followed by `of') a large number or amount or extent