legation n.

mid-12c., "authorized representative of the Pope," from Old French legat and directly from Latin legatus "ambassador, envoy," originally "provided with a commission," past participle of legare "send as a deputy, send with a commission, charge, bequeath," possibly literally "engage by contract" and related to lex (genitive legis) "contract, law," from PIE root *leg- (1) "to collect, gather." General sense of "ambassador, delegate, messenger of a state or authority" is from late 14c. in English. Related: Legator; legatee; legatine.