Confederacy
Part of speech: noun
Definition: an alliance
Example sentence: When a true genius appears, you can know him by this sign: that all the dunces are in a confederacy against him.
Federation
Part of speech: adjective
Definition: Of an architectural style popular around the time of federation.
Part of speech: noun
Definition: An array of nations or states that are unified under one central authority which is elected by its members.The act of joining several states into the federation. (Australia)
Example sentence: Frankly speaking, we don't see any other way for the steady development of the Ukrainian state apart from as a federation.