Envoy

Webster's Dictionary of the English Language

·noun An explanatory or commendatory postscript to a poem, essay, or book;

— also in the French from, l'envoi.

II. Envoy ·noun One dispatched upon an errand or mission; a messenger; ·esp., a person deputed by a sovereign or a government to negotiate a treaty, or transact other business, with a foreign sovereign or government; a minister accredited to a foreign government. An envoy's rank is below that of an Ambassador.