REGIONARIUS, re"gi-on-â'rî-us: In the premedieval Roman Church an official, primarily a deacon, placed over one of the ecclesiastical regions, originally seven in number, of the city of Rome. The institution is ascribed by the Liber pontificalis to both Clement I. and Fabian, the latter being the more probable. Each deacon was assisted by a subdeacon and a notary, while the Ordo Romanus also mentions regionary acolytes, and Gregory I. seems to have established "regionary defenders." The seven regionarii of Rome later became the cardinal deacons, whose number was raised to fourteen, and the regionary notaries were developed into the prothonotaries (see PROTHONOTARY APOSTOLIC).