1Roman Catholic Church
A papal envoy to a foreign court or government, ranking below a nuncio.
2A messenger or intermediary; a go-between.
3historical A diplomatic representative of a foreign government at the court of the Ottoman sultan, especially (in later use) a representative of the Austrian Empire.
Early 17th century; earliest use found in John Howson (?1557–1632), bishop of Durham. From Italian internunzio, †internuntio messenger, intermediary, papal envoy ranking below a nuncio from classical Latin internuntius.