An ecumenical council (or oecumenical council; also general council) is a conference of ecclesiastical dignitaries and theological experts convened to discuss and settle matters of Church doctrine and practice in which those entitled to vote are convoked from the whole world (oikoumene) and which secures the approbation of the whole Church.
The word "ecumenical" derives from the Late Latin oecumenicus "general, universal", from Greek oikoumenikos "from the whole world", from he oikoumene ge "the inhabited world (as known to the ancient Greeks); the Greeks and their neighbors considered as developed human society (as opposed to barbarian lands)", in later use "the Roman world" and in the Christian sense in ecclesiastical Greek, from oikoumenos, present passive participle of oikein "inhabit", from oikos "house, habitation." The first seven Ecumenical Councils, recognised by both the eastern and western denominations comprising Chalcedonian Christianity, were convoked by Christian Roman Emperors, who also enforced the decisions of those councils within the state church of the Roman Empire.
Starting with the third ecumenical council, noteworthy schisms led to non-participation by some members of what had previously been considered a single Christian Church. Thus, some parts of Christianity did not attend later councils, or attended but did not accept the results. Bishops belonging to what became known as the Eastern Orthodox Church accept only seven ecumenical councils, as described below. Bishops belonging to what became known as the Church of the East only participated in the first two councils. Bishops belonging to what became known as Oriental Orthodoxy participated in the first four councils, but rejected the decisions of the fourth and did not attend any subsequent ecumenical councils.
Acceptance of councils as ecumenical and authoritative varies between different Christian denominations. Disputes over christological and other questions have led certain branches to reject some councils that others accept.