from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. In Roman baths, the hottest room, with a plunge-pool. It preceded the tepidarium and frigidarium.
- n. In modern spas, a room with a hot floor.
from The Century Dictionary and Cyclopedia
- n. The Roman name for a stove or heating apparatus.
- n. A room in the Roman thermæ, or public baths, in which water was heated to the highest temperature. See bath, 5.
From Latin caldārium ("room containing warm water for bathing"), substantive of caldārius ("of, pertaining to or suitable for bathing"), from caldus ("warm, hot") + -ārius, alternative form of calidus, from caleō ("I am warm or hot; glow"). (Wiktionary)