Orthodox Church
noun
the Christian church comprising the local and national Eastern churches that are in communion with the ecumenical patriarch of Constantinople; Byzantine Church.
(originally) the Christian church of those countries formerly comprising the Eastern Roman Empire and of countries evangelized from it; Greek Orthodox Church.
British Dictionary definitions for orthodox church
Orthodox Church
noun
Also called: Byzantine Church, Eastern Orthodox Church, Greek Orthodox Church
the collective body of those Eastern Churches that were separated from the western Church in the 11th century and are in communion with the Greek patriarch of Constantinople
any of these Churches