An Etymological Dictionary of the German Language/Annotated/versöhnen

versöhnen (same as versühnen), verb, ‘to reconcile, atone for,’ from the equivalent Middle High German versüenen; allied to Sühne. The accented vowel is derived either from Low German or probably from Old Bavarian and Old Swabian, in which, late in the Middle Ages, œ appears before n., instead of üe (grön for grün; tön for tün).