baptistery, baptistry, baptisterium. Building or part of a church containing the font used for the Sacrament of Baptism, modelled on the cold bath, or baptisterium, of a Roman frigidarium in a therma, often consisting of a sunken circular pool in a circular building. Baptisteries such as those in Parma and Pisa were detached buildings, one polygonal and the other circular, and the form was recalled in some apsidal baptisteries physically joined to churches. Very often fonts are found in churches (usually at the west end), not screened off in any way, but if the area used for Baptism is demarcated by, e.g. a baptistery screen, or placed within an architectural element distinct from the nave or aisles, that arrangement is referred to as a baptismal enclosure.

baptistery XIV. — OF. baptister(i)e — ecclL. baptistērium — ecclGr. baptistḗrion.