Witch is close to old English wicca (=sorcerer).
And wicca is close to low German Wickewief = sorceress [wief =Weib= woman]
"wicken" is a verb in low German which means "to use magic".
I didn't know that Low German was still in use as a spoken language, now I know after consulting Wikipedia. I also learned that there are many variants of (spoken) German, and that for instance Swiss German is largely unintelligble for Germans (so, why is it called German?) Which makes sense - I've been in Switzerland a couple of times, and been spoken to in what sounded like German, but I couldn't understand anything.
pibbuR who knows that there are Norwegian dialects he has problems understanding, partially.