adjective

joined by an agreement or treaty.

some local groups united to form confederate councils

federal,confederated,federated,allied,in alliance,in league,cooperating,associated,united,combined,amalgamated

noun

a person one works with, especially in something secret or illegal; an accomplice.

where was his confederate, the girl who had stolen Richard’s wallet?

associate,partner,accomplice,abetter,accessory,helper,supporter,assistant,ally,collaborator,colleague,oppo,offsider

verb

bring (states or groups of people) into an alliance.

the treaty confederated the fourteen tribes