Yes, united is a Scrabble word!

Adjective

1. Characterized by unity; being or joined into a single entity

2. Of or relating to two people who are married to each other

Verb

1. Act in concert or unite in a common purpose or belief

2. Become one

3. Have or possess in combination

4. Be or become joined or united or linked

5. Bring together for a common purpose or action or ideology or in a shared situation

6. Join or combine