piscina

A stone basin with a drain for carrying away the water used in ceremonial ablutions.

A basin or tank, usually ornamental, as for a fountain or a bath; sometimes, a large shallow vase for ornamental fishes or aquatic plants; also, any tank or cistern of moderate size.

Eccles., a stone basin, in old churches generally established within a canopied niche placed close to the altar, used to receive the water in which the priest washes his hands before the celebration of the eucharist, and washes the chalice after the celebration. Now rarely used in the sanctuary, but often in sacristies.

A niche near the altar in a church, containing a small basin for rinsing altar vessels.

A drained basin near a church’s altar for the disposal of water from liturgical ablutions.