An Etymological Dictionary of the German Language/Klotz
Klotz, m. and n., ‘block, log, stump,’ from MidHG. kloz (gen. klotzes), m. and n., ‘lump, bullet,’ hence equiv. to MidHG. klôȥ; AS. *clott, E. clot; we may therefore assume Goth. *klutta-, the relation of which to klauta-, mentioned under Kloß, is evident. In the non-Teut. languages the Teut. root klut (‘bale’?), adduced under Kloß, has not been definitely authenticated; a root glud appears in Lith. gludus, ‘clinging to,’ glausti, ‘to cling to.’