Yes, mat is a Scrabble word!

Verb

1. Twist together or entwine into a confusing mass

2. Change texture so as to become matted and felt-like

Adjective

1. Not reflecting light; not glossy

Noun

1. A thick flat pad used as a floor covering

2. Mounting consisting of a border or background for a picture

3. Sports equipment consisting of a piece of thick padding on the floor for gymnastic sports

4. A mass that is densely tangled or interwoven

5. A master's degree in teaching

6. The property of having little or no contrast; lacking highlights or gloss

7. A small pad of material that is used to protect surface from an object placed on it