Outside the refectory usually stood a lavabo, or large basin for hand-washing.
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The room contains a lavabo and two tapestries by Van Assel representing Spring and Autumn.
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They may make use of a lavabo in preparation for the celebration and the chalice and paten may be initially concealed by a burse and ornamental veil.
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In Monaco's painting the angel and Mary are separated by two small spaces, one external and one internal, similar to the city-scape and domestic lavabo panels in the Ghent annunciation.
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More examples
Washbasin: a basin for washing the hands (`wash-hand basin' is a British expression)
A lavabo is a device used to provide water for the washing of hands. It consists normally of a ewer or container of some kind to pour water, and a bowl to catch the water as it falls off the hands. ...
A washbasin, especially one attached to the wall of a church, and used for the ceremonial washing of the hands of the celebrant before the eucharist
A bowl for the washing of hands, often in a religious institution.
A place found in monasteries where monks washed their hands before entering the church. In ecclesiastical terms, it refers both to the basin in which the monk or priest washes his hands and the ritual itself. In secular usage it refers to a handbasin.
A washbasin comprising a basin and fountain to supply water.
The part of Mass in which the priest washes his fingers before consecrating the bread and wine. from the Latin word meaning "I wash."
From Latin, meaning, "I will wash." The name originally referred to the ceremonial washing of the priests hands before he or she celebrated Communion, while saying the words, "I will wash my hands in innocence." (Psalm 26:6). ...