Envoy

Part of speech: noun (n.)

1. 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.

2. An explanatory or commendatory postscript to a poem, essay, or book; -- also in the French from, l'envoi. The envoy of a ballad is the "sending" of it forth. Skeat.