An Etymological Dictionary of the German Language/Kolben
Kolben, m., ‘club,’ from MidHG. kolbe, ‘mace, club, cudgel,’ OHG. cholbo, m.; Ic. kólfr, m., ‘javelin, arrow, bulb,’ with the derivative kylfi, n., kylfa, f., ‘club, cudgel.’ Goth. *kulba-n-, ‘stick with a thick knob at the end.’ From its meaning the word seems to be related to the cognates with the nasal form klumb, discussed under Klumpen; in that case the Aryan root may be gl-bh, and the word compared with Lat. globus, ‘round mass’ (also ‘clique,’ comp. E. club).