The warm, tepidus, a warm bathing room of the Roman baths heated by an underfloor heating system: "The specialty of a tepidarium was the pleasant feeling of constant radiant heat which directly affected the bathers from the walls and floor."

"The Tepidarium in the Roman thermae was a great central hall around which all the other halls were connected, and it provided the key to the setup of the thermae."

"The tepidaria were probably the halls where the bathers first got together before going through the various hot baths (Caldaria) or taking the cold bath (Frigidarium)."