An Etymological Dictionary of the German Language/Annotated/stammeln
stammeln, verb, ‘to stammer, stutter,’ from the equivalent Middle High German stammeln, stamelen, Old High German stammalôn, stamalôn. A derivative of Old High German stammal, stamal, ‘stammering,’ on whose earlier variant stammêr, stam-êr (nominative singular masculine), is based Old High German stammên, stamên, ‘to stammer.’ Compare the Gothic adjective stamms, Old Icelandic stamr, ‘stammering,’ and also stumm. The properly Low German stammern agrees with Dutch stameren, English to stammer (compare Anglo-Saxon stamor, ‘stammering’). For the root stam, ‘to check’ (stammeln, ‘to falter frequently’), see ungestüm and stemmen.