brothelyoudaoicibaDictYouDict[brothel 词源字典]
brothel: [14] Originally, brothel was a general term of abuse for any worthless or despised person (John Gower, in his Confessio Amantis 1393, writes: ‘Quoth Achab then, there is one, a brothel, which Micheas hight [who is called Micheas]’); it was a derivative of the Old English adjective brothen ‘ruined, degenerate’, which was originally the past participle of the verb brēothan ‘deteriorate’ (possibly a relative of brēotan ‘break’, which may be connected with brittle).

In the late 15th century we have the first evidence of its being applied specifically to a ‘prostitute’. Thence came the compound brothel-house, and by the late 16th century this had been abbreviated to brothel in its current sense.
[brothel etymology, brothel origin, 英语词源]
brothel (n.)youdaoicibaDictYouDict
"bawdy house," 1590s, shortened from brothel-house, from brothel "prostitute" (late 15c.), earlier "vile, worthless person" of either sex (14c.), from Old English broðen past participle of breoðan "deteriorate, go to ruin," from Proto-Germanic *breuthan "to be broken up," related to *breutan "to break" (see brittle). In 16c. brothel-house was confused with unrelated bordel (see bordello) and the word shifted meaning from a person to a place.