firebox

noun

Etymology: From fire + box. In the sense of a redheaded woman, from box (“vagina”).

1. The chamber of a steam engine, or a steam locomotive, in which the fuel is burned.

   “The firebox married to Britannia's boiler is not, however, in the Doncaster tradition, notwithstanding that it is comparable in dimensions to that of the "V2." […] Britannia's firebox would appear to have derived from those of the Bulleid Pacifics, which it closely resembles.”

2. The part of a fireplace where the fuel is burned.
3. A redheaded woman or her red pubic hair.