Lewis & Short

† baptistērĭum, ii, n., = βαπτιστήριον.

  1. I. A place for bathing or swimming, a vessel for bathing, Plin. Ep. 5, 6, 25; 2, 17, 11; Sid. Ep. 2, 2.
  2. II. In eccl. Lat., a baptistery, a baptismal font, Sid. Ep. 4, 15.