OKay, this is not an accurate etymology, but this is what a lot of Pagan books cite, so I thought I'd let people see it:
(Appendix to Jeffery Burton Russell's "history of Witchcraft") The ultimate origin of the English word 'witch' is the Indo-European root *weik2, which has to do with religion and magic. *Weik2 produced four families of derivatives: 1. *wih-l, which yielded Old English 'wigle', 'sorcery', and 'wiglera,' 'sorcerer,' and, through Old and Middle French, modern English 'guile.' Also Old English 'wil', Middle and modern English 'wile.' 2. *Old Norse *wihl-, 'craftiness.' _ 3. *wik-, 'holy,' whence Old High German 'wihen' and German 'weihen,' 'to consecrate,' Middle High German wich, 'holy,' and Latin 'victima,' 'sacrifice. 4. *wikk- 'magic, sorcery,' whence Middle German 'wikken,' 'to predict,' and Old English 'wicca, wicce, 'witch' and 'wiccain,' 'to work sorcery, bewitch.' From 'wicca' derives Middle English 'witche' and Modern English 'witch'. Different from *weik2 and its derivations is *weik4, 'bending', whence Old English 'wican,' 'to bend,' fromw hich the modern English 'weak' and 'witch-elm.' Related to 'wican' are Old Saxon 'wikan,' Old High German 'wichan,' old Norse 'vikja,' all meaning 'to bend, or turn aside.' Oldd English 'witan,' 'to know,' and all related words including 'wise' are totally unrelated to either of the above.