proconsul (in ancient Rome)
proconsul, in ancient Rome, governor of a province. He was in sole charge of the army, of justice, and of administration in his province and could not be prosecuted for maladministration until his office expired. In modern times the title has sometimes been used for a colonial governor with far-reaching powers.
See W. M. Jashemski, The Origin and History of the Proconsular and the Propraetorian Imperium to 27 BC (1950).