Bishopric means the office, responsibility, or sphere associated with a bishop’s oversight. The supplied material also describes it as the district over which a bishop’s jurisdiction extended.
The term is connected with the overseership or position of responsibility mentioned in Acts 1:20 and 1 Timothy 3:1. It refers to the work or office of oversight rather than merely to a geographical area.
In later usage, bishopric could denote the district governed by a bishop. The supplied material does not provide further historical detail.