From Greek presbyteros ("elder"). The system of church government in which authority is exercised through a graded hierarchy of elder-ruled courts: (1) the session (elders of a single local church); (2) the presbytery (elders from multiple churches in a region); (3) the synod (several presbyteries); (4) the general assembly (the national body). Appeals move up this chain; decisions of lower courts may be reviewed by higher courts. This system originated with the Reformed wing of the Reformation — Calvin in Geneva, Knox in Scotland — and is now the polity of Presbyterian, Reformed, and some Dutch Reformed and Hungarian Reformed churches.
The Presbyterian case is also biblical in ways worth weighing. (1) Elder-rule — the NT explicitly commits local church governance to a plurality of elders (see Plurality of Elders entry); (2) Connectionalism — the Jerusalem Council (Acts 15) shows churches working together to resolve doctrinal disputes that transcended any single congregation; Paul and Barnabas took the Antioch question to "the apostles and elders" at Jerusalem, whose judgment then bound both churches. (3) Appeals — serious disputes may need review by those outside the original local setting, preventing local tyrannies. Where Presbyterian polity risks going wrong is in growing the hierarchy's power at the expense of the local church. When a general assembly dictates what a local church may teach or who may commune, it has exceeded its Jerusalem Council mandate (which gave a recommendation the local churches then adopted, not a ruling overriding congregational responsibility). Well-practiced Presbyterianism holds elder rule and connectionalism together without swallowing the local church. Healthy Presbyterianism and healthy congregationalism actually look more alike than polemicists on either side admit: both emphasize plural elder leadership, both take seriously the authority of the whole body, and both resist top-down authoritarianism. The New Testament does not mandate a single polity in every detail — but it gives principles that should shape whatever polity a church adopts.