baptistry

/B AE1 P T AH0 S T R IY0/
noun
  1. 1

    A designated space within a church, or a separate room or building associated with a church, where a baptismal font is located, and consequently, where the sacrament of Christian baptism (via aspersion or affusion) is performed.

  2. 2

    An indoor pool used for baptism by immersion.

Source: https://en.wiktionary.org/wiki/baptistry