WordWeb Online

1. United under a central government
   - federate

1. Enter into a league for a common purpose
   "The republics federated to become the Soviet Union"
   - federalize, federalise [Brit]
    
2. Unite on a federal basis or band together as a league
   "The country was federated after the civil war"
   - federalize, federalise [Brit]

See also: federation, united

Type of: merge, unify, unite

Encyclopedia: Federate