- Historical the Christian Church in much of the eastern part of the Roman Empire, consisting of the four patriarchates in E Europe, W Asia, and Egypt, headed by the bishops of Constantinople, Alexandria, Antioch, and Jerusalem
- Eastern Orthodox Church
- collectively, the Eastern Christian churches in communion with the Western churches
- The church of the Byzantine Empire, including the patriarchates of Constantinople, Antioch, Alexandria, and Jerusalem.
- The Eastern Orthodox Church.
- often Eastern church The set of Christian churches centered in southwest Asia, northeast Africa, and Eastern Europe, including the Eastern Orthodox, Oriental Orthodox, Nestorian, and Eastern Catholic churches.