In the Eastern Orthodox Church, the endemic synod[a] or endemousa synodos (Greek: ἐνδημοῦσα σύνοδος) was the permanent standing synod of bishops of the Patriarchate of Constantinople that met frequently but irregularly to deal with issues of discipline and dogma.
Only metropolitan bishops, autocephalous archbishops and the administrative functionaries of the patriarch (of which there were five) were permitted to attend meetings.
[2] During the 11th-century Byzantine–Seljuq wars, a number of bishops fled to Constantinople and the size of the synod increased.
[4] The endemousa synodos lasted through the end of the Byzantine Empire (1453) and continued under the Ottomans.
In the 18th century, its remit was limited to strictly spiritual affairs and it was renamed the Holy Synod.