1911 Encyclopædia Britannica/Lavabo

LAVABO (Lat. “I will wash”; the Fr. equivalent is lavoir), in ecclesiastical usage, the term for the washing of the priests’ hands, at the celebration of the Mass, at the offertory. The words of Psalm xxvi. 6, Lavabo inter innocentes manus meas, are said during the rite. The word is also used for the basin employed in the ritual washing, and also for the lavatories, generally erected in the cloisters of monasteries. Those at Gloucester, Norwich and Lincoln are best known. A very curious example at Fontenay, surrounding a pillar, is given by Viollet-le-Duc. In general the lavabo is a sort of trough; in some places it has an almery for towels, &c.