in the ancient baths, denoted a brazen vessel or cistern, placed in the hypocaustum, full of hot water, to be drawn thence into the piscina or bath, to give it the necessary degree of heat. In this sense the caldarium stands contradistinguished from the tepidarium and frigidarium.

Caldarium also denoted the stove or sudatory, being a close vaulted room, in which, by hot dry fumes, without water, people were brought to a profuse sweat. In this sense caldarium was the same with what was otherwise denominated vaporarium, sudatorium, and laconium; and in the Greek baths, hypocaustum, leucauenos.