An Etymological Dictionary of the German Language/Annotated/schwindeln

by Friedrich Kluge

schwindeln, verb, ‘to be dizzy or giddy,’ from the equivalent Middle High German swindeln, Old High German swintilôn, allied to Middle High German swindel, ‘giddiness, vertigo,’ equivalent to Old High German swintilôd and swintilunga. Further akin to schwinden, ‘to dwindle away,’ hence Middle High German also ‘to faint, become unconscious.’