Yes, mates is a Scrabble word!

Verb

1. Engage in sexual intercourse

2. Bring two objects, ideas, or people together

3. Place an opponent's king under an attack from which it cannot escape and thus ending the game

4. Twist together or entwine into a confusing mass

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

Noun

1. A pair of people who live together

2. The officer below the master on a commercial ship

3. A fellow member of a team

4. The partner of an animal (especially a sexual partner)

5. A person's partner in marriage

6. An exact duplicate

7. One of a pair

8. South American holly; leaves used in making a drink like tea

9. Informal term for a friend of the same sex

10. South American tea-like drink made from leaves of a South American holly called mate

11. A chess move constituting an inescapable and indefensible attack on the opponent's king