federation n.

Proto-Indo-European root meaning "to trust, confide, persuade."

It forms all or part of: abide; abode; affiance; affidavit; auto-da-fe; bide; bona fide; confederate; confidant; confide; confidence; confident; defiance; defy; diffidence; diffident; faith; fealty; federal; federate; federation; fiancee; fideism; fidelity; fiducial; fiduciary; infidel; infidelity; nullifidian; perfidy; solifidian.

It is the hypothetical source of/evidence for its existence is provided by: Greek pistis "faith, confidence, honesty;" Latin fides "trust, faith, confidence, reliance, credence, belief;" Albanian be "oath," bindem "to be convinced, believe;" Old Church Slavonic beda "distress, necessity," bediti "to force, persuade;" Old English biddan "to ask, beg, pray," German bitten "to ask."

1814 (implied in federated), a back-formation from federation, or else from Latin foederatus "leagued, federated, combined; having a treaty, bound by treaty," past participle of foederare "to establish by treaty," from foedus "covenant, treaty, alliance" (from PIE root *bheidh- "to trust, confide, persuade"). Related: Federating. As an adjective, by 1710.