An Etymological Dictionary of the German Language/stottern
stottern, vb., ‘to stutter, stammer,’ ModHG. only (in Swab. gaksen, Austr. štückezen), formed from MidG. and LG., in which stotteren (so too in Du.) is an intensive of stoten, ‘to push, thrust’ (stottern, lit. ‘to stumble repeatedly’); corresponding to E. to stutter. See the preceding word.