calefactory

Latin: calefacere, to warm

1) The heated room in an English monastery where the monks retired occasionally to warm themselves, especially after Matins.

2) A hollow globe of precious metal containing hot water, to warm the priest‘s fingers when administering Holy Communion in cold weather; a silver one, gilded and, carved with leaves, and weighing 9.5 ounces, was in use at Lincoln Cathedral in 1281.