Lewis & Short

balnĕārĭus (bălĭneārĭus, Inscr. Grut. 171, 8), a, um, adj. [balneum], of or pertaining to a bath (class. for the preced.): fur, lurking about baths, Cat. 33, 1; cf. the title in Dig. 47, 17: de furibus balneariis: furtum, Dig. 1. 1. § 3: instrumentum, a bathing implement, ib. 33, 7, 17: vapores, ib. 43, 21, 3, § 6.
Subst.: balnĕārĭa, ōrum, n. plur., a place for bathing, a bathing-room, bath: nihil ei restabat praeter balnearia et ambulationem et aviarium, Cic. Q. Fr. 3, 1, 1, § 1; so id. Att. 13, 29, 2; Col. 1, 6, 2; Sen. Q. N. 4, 9; id. Tranq. 9, 7.