from The Century Dictionary.
- noun A title given to various Roman Catholic ecclesiastics who are assigned to duty in or jurisdiction over certain regions or districts in the city of Rome.
Sorry, no etymologies found.
As the deacons were assisted by seven subdeacons, we also find the term subdeaconus regionarius.
Many branches of the ecclesiastical administration were arranged in accordance with the seven regions — especially the care of the poor, provision for the maintenance of the churches, and whatever else pertained primarily to the office of the deacons, one of whom was appointed over each of the seven regions (diaconus regionarius).