The Collaborative International Dictionary
Baptistries
Baptistery \Bap"tis*ter*y\,Baptistry \Bap"tis*try\, n.; pl. Baptisteries, Baptistries. [L. baptisterium, Gr. baptisth`rion: cf. F. baptist[`e]re.] (Arch.)
In early times, a separate building, usually polygonal, used for baptismal services. Small churches were often changed into baptisteries when larger churches were built near.
A part of a church containing a font and used for baptismal services.
Wiktionary
baptistries
n. (plural of baptistry English)