The word is French. The Greek word for Diplomat was proxenos (πρόξενος). It has Greek origin as it originates from word diplono (διπλώνω means to fold) because diplomats always gave their credententials folded.
Diplomacy / Diplomat

But you don't know it
Explore ‘genocide’, a term combining Greek ‘genos’ (race) and Latin ‘caedere’ (to kill), signifying the mass extermination of groups
Democracy from greek word δημοκρατία (demokratia from greek word démos people and krάtos – rule, govern). So people take part on the decisions, take governors positions and are responsible to follow the orders of the people. In ancient Athens, the first democracy, if a man fall to respond to his[…]
Trace ‘tyranny’ from Greek ‘tyrannos’ to its negative connotation, including Athens’ shift from popular rulers to oppressors.