Definition of hotboxes:
(n) :
A container maintained at elevated temperatures in order to heat or cook its contents.
(n) :
An oven.
(n) :
(engineering) An overheated shaft bearing.
(n) :
(rail transport) An overheated axle box, bearing and bearing enclosure.
(n) :
A room or compartment that is kept artificially warm for some purpose.
(n) :
A cold frame containing compost that provides a limited amount of warmth.