verb (used with or without object), fed·er·at·ed, fed·er·at·ing.
- federated; allied.
- to unite or cause to unite in a federal union
- federal; federated
1814 (implied in federated), back-formation from federation, or else from Latin foederatus “having a treaty, bound by treaty,” past participle of foederare “to establish by treaty,” from foedus (see federal). Related: Federating. As an adjective, by 1710.