Lewis & Short

lŭpānar, āris, n. [lupa, II. A.], a house of ill-repute: qui in lupanari accubat, Plaut. Bacch. 3, 3, 50: deprehensus in lupanari cum alienā uxore, Quint. 7, 3, 6: intrare, Juv. 6, 121: virorum, Mos. et Rom. Leg. Coll. 5, 3, 2.
As a term of reproach: O lutum, lupanar, aut si perditius potest quid esse, Cat. 42, 13.