Lavabo

A lavabo is a device used to provide water for the washing of hands. It consists normally of an ewer or container of some kind to pour water, and a bowl to catch the water as it falls off the hands. In ecclesiastical usage it refers to all of: the basin in which the priest washes his or her hands; the ritual that surrounds this action in the Mass; and the architectural feature or fitting where a basin or place for one is recessed into the side wall of the sanctuary, or projects from it. If this last includes or included a drain, it is a piscina used for washing the church plate and other fittings, though the terms are often confused. In secular usage, it is an obsolete term for any sink or basin for washing hands, especially in a lavatory.

Ecclesiastical usage

The name lavabo ("I shall wash" in Latin) is derived from the words of Psalm 26:6-12 (KJV; in the Septuagint it is Psalm 25), which the celebrant traditionally recites while he washes his hands: "I will wash my hands in innocency, so will I compass thine altar, O Lord". The washing of hands during the recitation of these psalm verses is of very ancient usage in the Catholic Church: