A synod historically is a council of a church, usually convened to decide an issue of doctrine, administration or application. In modern usage, the word often refers to the governing body of a particular church, whether its members are meeting or not. It is also sometimes used to refer to a church that is governed by a synod.

The word synod comes from the Greek σύνοδος meaning "assembly" or "meeting", and it is synonymous with the Latin word concilium — "council". Originally synods were meetings of bishops, and the word is still used in that sense in Catholicism and Eastern Orthodoxy.

Sometimes the phrase general synod or general council refers to an ecumenical council. The word synod also refers to the standing council of high-ranking bishops governing some of the autocephalous Eastern Orthodox churches. Similarly, the day-to-day governance of patriarchal and major archiepiscopal Eastern Catholic Churches are entrusted to a permanent synod.

In Orthodox churches, synods of bishops are meetings of bishops within each autonomous Church and are the primary vehicle for the election of bishops and the establishment of inter-diocesan ecclesiastical laws.