apodyterion, -a
An undressing room, next to the entrance in a bathhouse, or a gymnasium, or a palaestra.

caldarium
Derivative of the Latin verb caleo (= warm up). It is the strongly heated room of Roman baths. Its hot plunge pool was used to take not only a hot bath but also a steam bath due to high levels of humidity. It was also called the "inner room".

frigidarium
A large cold pool to drop into after enjoying a hot Roman bath (from frigeo). Normally frigidarium has used after a visit to warm rooms (caldarium) or after a training in palaistra. As the largest room in the thermae and often functioned as a hall for social events or communication

hypocaust, the
the main system for the heating of ancient baths. The word means literally a “furnace that burns underneath”. With this system the room’s floor was supported by small poles and the space underneath the floor was heated by the circulation of hot air, while the heat was transferred through the walls by conductors.

imperial type of baths
The baths of the imperial type have large chambers arranged in the central part of the ground plan (cold, warm and hot chambers), while the auxiliary rooms are arranged symmetrically along the sides of the complex.

laconicum (archit.)
The hot chamber for dry sweating in Roman baths. It is of circular shape, according to Vitruvius.

niche
Semi-circular recess on the surface of the wall.

palaestra
A colonnaded enclosure for athletic exercise. The palaestra functioned both independently and as a part of the Greek gymnasium. It was formed as an open court surrounded by colonnades with adjoining rooms.

sudatorium
It is the architectural term, deriving from the latin verb "sudo" (=sweat), for the sweating room of the roman baths. It is usually a vaulted room of rectangular form between the caldarium and the tepidarium. In the Early Roman times (1st- 2nd c. B.C.) sudatoria used to be of circular form.

tepidarium
The word is derived from the verb tepeo meaning ‘to be tepid’. It is the room of tepid water in the Roman thermae. It was also called middle house or tepid house and was usually situated between the caldarium and the frigidarium. Its main function was the acclimatization of the bather to the change of temperature. Being at the Tepidarium the visitor could also apply ointments on his/her body before or after the hot bath, although, there was a special room for this function called unctorium.

thermae
Building complexes dated in the Roman Period housing the public baths. Within the building there were three rooms, the frigitarium, the tepidarium and the caldarium and several other facilities rooms. The Roman bath-houses were also used as meting places and they often included a palaestra and a gymnasium.

vault
A semi-cylindrical roof.