Official principal
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
An ecclesiastical officer whose duty it is to hear causes between party and party as the delegate of the bishop or archbishop by whom he is appointed. He generally also holds the office of vicar general and (if appointed by a bishop) that of chancellor. The official principal of the province of Canterbury is called the "dean of arches " Phillim Ecc. Law, 1203, et seq.; Sweet.