In those hierarchically organised churches of Western Christianity which have an ecclesiastical law system, an ordinary is an officer of the church who by reason of office has ordinary power to execute the church's laws. The term comes from the Latin word ordinarius. In Eastern Christianity, a corresponding officer is called a hierarch, which comes from the Greek word ἱεράρχης meaning "priestly ruler".
In canon law, the power to govern the church is divided into the power to make laws (legislative), enforce the laws (executive), and to judge based on the law (judicial). A person exercises power to govern either because the person holds an office to which the law grants governing power or because someone with governing power has delegated it to the person. Ordinary power is the former, while the latter is delegated power. The office with ordinary power could possess the governing power itself (proper ordinary power) or instead it could have the ordinary power of agency, the inherent power to exercise someone else's power (vicarious ordinary power).