The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
weik-2
DEFINITION:
Also weig-. To bend, wind. Derivatives include wicker, weak, and vicarious. I. Form *weig-.1a.wych elm, from Old English wice, wych elm (having pliant branches); b.wicker, from Middle English wiker, wicker, from a Scandinavian source akin to Swedish viker, willow twig, wand; c.wicket, from Old North French wiket, wicket (< door that turns), from a Scandinavian source probably akin to Old Norse vikja, to bend, turn. ac all from Germanic *wik-.2a.weak, from Old Norse veikr, pliant; b.weakfish, from Middle Dutch weec, weak, soft. Both a and b from Germanic *waikwaz.3.week, from Old English wicu,wice, week, from Germanic *wikn-, a turning, series. II. Form *weik-. Zero-grade form *wik-.a.vicar, vicarious, vice-; vicissitude, from Latin *vix (genitive vicis), turn, situation, change; b.vetch, from Latin vicia, vetch (< twining plant). (Pokorny 4. eik- 1130.)