Federate

['fedəreɪt] or ['fɛdəret]

(verb.) unite on a federal basis or band together as a league; 'The country was federated after the civil war'.

(verb.) enter into a league for a common purpose; 'The republics federated to become the Soviet Union'.

(adj.) united under a central government .

Checked by Clive--From WordNet

(a.) United by compact, as sovereignties, states, or nations; joined in confederacy; leagued; confederate; as, federate nations.

Edited by Donnie