Definitions for "Caldarium"
heated room in the thermae were hot sit-baths were taken.
The steam room of a Roman bath.
This was hottest room in regular sequence of bathing rooms. It is described in detail by Vitruvius (5.10.4, see also 8.2.4) and mentioned by Pliny ( Ep. 5.6.25) who terms it a cella caldaria. Sidonius Apollinaris ( Ep. 2.2.4) uses the term cella coctilium, the "room of the dry wood (for burning)." It's form and function have been fully studied by modern scholars such as Nielsen and Yegül.