A cathedral (French cathédrale from Latin. cathedra, "seat" from the Greek kathedra (καθέδρα), seat, bench, from kata "down" + hedra seat, base, chair) is a Christian church which contains the seat of a bishop, thus serving as the central church of a diocese, conference, or episcopate. Although the word "cathedral" is sometimes loosely applied, churches with the function of "cathedral" occur specifically and only in those denominations with an episcopal hierarchy, such as the Roman Catholic, Anglican, Orthodox, and some Lutheran and Methodist churches. In the Greek Orthodox Church, the terms kathedrikos naos (literally: "cathedral shrine") is sometimes used for the church at which an archbishop or "metropolitan" presides. The term "metropolis" (literally "mother city") is used more commonly than "diocese" to signify an area of governance within the church.

There are certain variations on the use of the term "cathedral"; for example, some pre-Reformation cathedrals in Scotland now within the Church of Scotland still retain the term cathedral, despite that church's Presbyterian polity that does not have bishops. The same occurs in Germany, where Protestant churches (many with a presbyterian or congregational polity) co-operate under an umbrella organisation, the Evangelical Church in Germany, with some retaining cathedrals or using the term as a merely honorary title and function, void of any hierarchical supremacy. As cathedrals are often particularly impressive edifices, the term "cathedral" is often applied colloquially to any large and impressive church, regardless of whether it functions as a cathedral, such as the Crystal Cathedral in California or figuratively to imply that a church is of outstanding beauty such as St John the Baptist, Tideswell, known as the "Cathedral of the Peak".