Green’s Dictionary of Slang

1. (US, also boarding lady) an inmate of a brothel.

1842		Whip & Satirist of NY & Brooklyn (NY) 16 Apr. n.p.: Quite a change has taken place at the Mansion of Miss Mary Shaw [...] One of the boarders, Miss Caroline Greene, is confined to her bed by a fever.
1842		Whip & Satirist of NY & Brooklyn (NY) 3 Dec. n.p.: Her establishment is ther ‘crack’ of the city for boarding ladies amnd their ‘friends’.
c.1850		Peeping Tom (London) 10 38/1: The boarders of these houses are obliged to [...] decoy any straggling young man who may reel in from the tavern.
1851		Life in Boston & N.Y. (Boston, MA) 4 Jan. n.p.: Who should we come across but several of the ‘boarders’ at Mrs Dean’s establishment.
1861		N.E. Police Gaz. (Boston, MA) 5 Oct. 7/3: Old Begg [...] has five or six fancy boarders. Call in, boys. Price, only a two spot.
1880		Nat. Police Gaz. (NY) 25 Sept. 10/3: Poor Josie McQueen [...] sank lower and lower until she finally became a ‘boarder’ with the notorious Ruby Bell.

2. (Aus. prison) a prison inmate.

1901		Sydney Sportsman (Surry Hills, NSW) 2 Jan. 4/1: I ventured to state that the Christmas Day demons were not perfect gentlemen: in fact [...] that would be warmly welcomed by their pals the boarders at Berrima.
1949		Cessnock Eagle (NSW) 4 Oct. 4/2: They took a picture to identify me. / Then forty demons said ‘just nod your head and you’ll be free’ / So I pleaded ‘Guilty’ just like a ‘gay’ / Now I’m a boarder out at Long Bay.