Tepidarium, tepidarij, n. g. Paulus, iuriscons. A baine, stewes or hote house.Tepidarium. Vitru. A vessel wherin water is made warme.
Lewis and Short: Latin dictionary
tĕpĭdārĭus, a, um, adj. [tepidus], of or belonging to tepid water or to a tepid bath.I.Adj.: aënum, Vitr. 5, 10: CELLA, Inscr. Orell. 3328. — II.Subst.: tĕpĭdārĭum, ii, n., a tepid bathing-room, tepid bath, Cels. 1, 3; Vitr. 5, 10, 1 and 5.