WordWeb Online

1. Put under the control and authority of a federal government
   - federalize
    
2. Enter into a league for a common purpose
   "The republics federalised to become the Soviet Union"
   - federate, federalize
    
3. Unite on a federal basis or band together as a league
   "The country was federalised after the civil war"
   - federate, federalize

Derived forms: federalising, federalised, federalises

See also: federalisation [Brit]

Type of: decentralise [Brit], decentralize, deconcentrate, merge, unify, unite