văpōrārĭum, ii, n. [vapor],
a steam-pipe in the Roman baths, which conveyed the heat to the sweating-room, Cic. Q. Fr. 3, 1, 1, § 2; Sen. Q. N. 3, 24, 3 Haase.
vapōrārium ī, n vapor, a steam-chamber, sweating-room (in a bath). ...
An Elementary Latin Dictionary