1) a clibanus, an 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
Part of Speech: noun masculine
Of uncertain derivation; an earthen pot used for baking in: - oven.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root κλίβανος; click on the second column to search for that grammatical form of the root κλίβανος; click on the third column to search for that word and grammatical form; click on the total to search for the root κλίβανος.