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n. A warm room in a Roman baths that was usually heated by a hypocaust

n. In the ancient Roman baths, an apartment heated to a certain temperature to prepare the body for the great heat of the hot and vapor baths, or to serve as a palliative to the cold of the frigidarium; also, the boiler in which the water was heated for the hot bath.

"The Roman-style baths include an apodypterium , or changing room; a tepidarium , or warm room; and a caldarium , or hot room, along with a domed chamber for housing firewood."

caldarium    frigidarium   

appurtenance    appanage