1) clay, potter's earth
2) anything made of clay, earthen ware
3) a roofing tile
3a) the roof itself
3b) the phrase "through the roof", means through the door in the roof to which a ladder or stairway led up from the street (according to the Rabbis distinguish two ways of entering a house, "the way through the door" and "the way through the roof"
Part of Speech: noun masculine
Probably from the base of G2767 (through the idea of mixing clay and water); earthenware, that is, a tile (by analogy a thin roof or awning): - tiling.
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 κέραμος; click on the second column to search for that grammatical form of the root κέραμος; click on the third column to search for that word and grammatical form; click on the total to search for the root κέραμος.