An Etymological Dictionary of the German Language/ungestüm

by Friedrich Kluge

ungestüm, adj., ‘blustering, impetuous,’ from MidHG. ungestüeme, OHG. ungistuomi (unstuom), adj., ‘stormy, impetuous’; the unnegatived form of the adj. was extremely rare in OHG. and MidHG. Based on a verbal root stam, as in MidHG. stęmen (ModHG. stemmen, from *stamjan), ‘to check, restrain,’ which appears also in ModHG. stammeln. —