From WordNet (r) 2.0 (August 2003) [wn]:
brothel
n : a building where prostitutes are available [syn:
whorehouse, bordello, bagnio, {house of
prostitution}, house of ill repute, bawdyhouse,
cathouse, sporting house]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Brothel \Broth"el\, n. [OE. brothel, brodel, brethel, a
prostitute, a worthless fellow, fr. AS. ber['o][eth]an to
ruin, destroy; cf. AS. bre['o]tan to break, and E. brittle.
The term brothel house was confused with bordel brothel. CF.
Bordel.]
A house of lewdness or ill fame; a house frequented by
prostitutes; a bawdyhouse.
[1913 Webster]