la·va·bo /ləˈveɪboʊ, -ˈvɑ-/
–noun, plural -boes.
a. the ritual washing of the celebrant’s hands after the offertory in the Mass, accompanied in the Roman rite by the recitation of Psalm 26:6–12.
b. the passage recited.
c. the small towel or the basin used.
2. (in many medieval monasteries) a large stone basin equipped with a number of small orifices through which water flowed, used for the performance of ablutions.
3. a washbowl with a spigot-equipped water tank above, both mounted on a wall: now often used for decoration or as a planter.
1855–60; < L lavābō: I shall wash
The abbot was waiting for us next to a little fountain, with a white cloth to wipe our hands after the lavabo, following the ancient counsels of Saint Pachomius.
Source: The Name of the Rose by Umberto Eco.