An Etymological Dictionary of the German Language/Annotated/wenden

by Friedrich Kluge

wenden, verb, ‘to turn, change,’ from Middle High German węnden, Old High German węnten (from *wantjan), weak verb, ‘to overturn, cause to retrograde, hinder.’ Compare Old Saxon węndian, Gothic wandjan, Anglo-Saxon węndan, ‘to turn,’ English to wend, Dutch wenden, ‘to change’; a factitive of winden. Hence auswendig, ‘by heart,’ Middle High German ûȥwęndic, ‘externally, abroad’ (etwas auswendig können is a Modern High German phrase, and is here used in the sense of ‘externally,’ i.e., ‘without looking into a book’); inwendig, ‘internally,’ from Middle High German innęwendec. —