assembly convened to deliberate and decide on ecclesiastical doctrine and on other matters affecting the interests of the Christian church. Before the 12th century the term council was used synonymously with the term synod. The latter word, however, is now employed in a restricted sense to designate a diocesan council, a council that comprises the clergy of a diocese and is usually presided over by a bishop. Other councils, in ascending hierarchical order, are provincial, primatial, national, patriarchal, and general or worldwide assemblies.

When the pope summons representatives of the church from the entire Roman Catholic world to a council whose decisions he approves by an explicit and formal act, that council thenceforth is called an ecumenical council. Before the first Lateran council was called by Pope Callistus II in 1123, the emperors of Constantinople, who were the nominal protectors of the church, summoned ecumenical councils; since 1123, the councils must be summoned by the pope and presided over by him or his legates. Theoretically, an ecumenical council is any council whose findings are explicitly approved by the pope, but ecumenical councils have usually been called as general councils. This fact has given rise to the use of the term ecumenical (from Gr. oikoumene, “the inhabited world”) as synonymous with general, when applied to a council.

The first meeting of Christians that could be called a council is described in Acts 15:1–31. This so-called Council of Jerusalem was a meeting of Peter, Paul, and the leaders of Jerusalem‘s Christians about ad 50. It discussed the means by which Gentiles could be converted.

Twenty-one ecumenical councils are listed in the annals of the Roman Catholic church, according to the places in which they were held. Members of the Orthodox church and many Protestants acknowledge the authority of only the first seven of these councils. Martin Luther accepted only the first four councils.

Among Protestant churches, bodies equivalent in authority to the ecumenical councils of the Roman Catholic church include the general assemblies of the Presbyterian denomination, the general conferences of the Methodist denomination, and the general conventions of the Protestant Episcopal church. The term council is also applied by Protestant denominations to assemblies convened to deal with doctrinal and administrative matters. These councils, however, do not have the authority of the councils of the Roman Catholic church; in the Baptist and Congregational denominations, for example, the national councils are merely advisory assemblies.