An Etymological Dictionary of the German Language/stumm

by Friedrich Kluge

stumm, adj., ‘dumb, silent,’ from the equiv. MidHG. and OHG. (and OSax.) stum (mm); corresponding to Du. stom, ‘dumb.’ Its connection with the cognates of stammeln (root stam) is undoubted. MidHG. stęmmen, OHG. stęmmen (from stamjan), ‘to stop, check’ (comp. stemmen and ungestüm), shows that stammeln and stumm sein mean lit. ‘to falter (in speaking).’