tepidarium

Tepidarium, from the Latin tepidus meaning lukewarm, is a warm room in a Roman thermae (public bathhouse). It served as a transitional space between the hot caldarium and the cold frigidarium, allowing bathers to acclimate to heat and rest between baths.

Architecturally, the tepidarium was typically heated by the hypocaust, an underfloor heating system that circulated hot air through floors and walls. It often featured benches along the walls and, in some sites, a shallow pool or basin. The temperature was moderate compared with the steamy caldarium and the cool frigidarium, providing a comfortable environment for drying and relaxation.

Within the bath complex, the tepidarium occupied a central role in the sequence of bathing, often located between the hot and cold rooms so bathers could move progressively from heat to cold. The exact furnishings varied by site; some tepidaria included a warm pool, while others were primarily dry rooms with seating for rest and socializing.

Evidence of tepidaria is found throughout Roman thermae in Italy and the provinces, including sites at Pompeii, Herculaneum, and Britain’s Bath, among others. The term tepidarium is used in modern scholarship to describe this type of room, preserving the Roman approach to a structured bathing experience focused on hygiene, relaxation, and social interaction.