Thayer's Greek Lexicon

 1. a clibanus, a earthen vessel for baking bread. It was broader at
the bottom than above at the orifice, and when sufficiently heated
by a fire kindled within, the dough was baked by being spread upon
the outside. [but according to others, the dough was baked by
being placed inside and the fire or coals outside, the vessel
being perforated with small holes that the heat might better
penetrate.
2. a furnace, oven