Green’s Dictionary of Slang

sweat-box n.

[note ‘The original “sweat box” used during the period following the (US) Civil War [...] was a cell in close proximity to a stove, in which a scorching fire was built and fed with old bones, pieces of rubber shoes etc, all to make great heat and offensive smells, until the sickened and perspiring inmate of the cell confessed in order to get released’ (deposition to the Rep. Nat. Comm. Law Observance & Enforcement, 1931)]

1. [mid-19C–1950s] any small, hot room, or place.

2. [mid-19C+] (orig. US) an oppressively small cell; a punishment cell.

3. [late 19C+] a room, usu. in a police station, in which prisoners undergo interrogation; also attrib.

4. [late 19C] (US) the upper gallery of a theatre.

5. [late 19C+] a cell for prisoners waiting to appear in a magistrate’s court.

6. the equivalent of an SE sweat shop.

7. [1950s] (US) one who is sweating heavily.

8. [1970s] (US black) a crowded party.

9. [1970s+] a prison van, used to transport prisoners from court to prison etc.