1A messenger or mediator between two parties; especially (in early use) an intermediary between God and mankind.
2Roman Catholic Church
A papal envoy to a foreign court or government; = internuncio . Now chiefly historical and rare.
3historical, rare A diplomatic representative of a foreign government at the court of the Ottoman sultan; especially a representative of the Austrian Empire; = internuncio .
Mid 17th century. From classical Latin internuntius messenger, intermediary from inter- + nuntius.