wych

1540s, probably from Old English wice "Applied generally or vaguely to various trees having pliant branches" [OED], from wican "to bend" (from PIE root *weik- (2) "to bend, to wind") + hæsel, used for any bush of the pine family (see hazel (n.)). The North American bush, from which a soothing lotion is made, was so called from 1670s. This is the source of the verb witch in dowsing.

also *weig-, Proto-Indo-European root meaning "to bend, to wind."

It forms all or part of: vetch; vicar; vicarious; vice- "deputy, assistant, substitute;" viceregent; vice versa; vicissitude; weak; weakfish; week; wicker; wicket; witch hazel; wych.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit visti "changing, changeable;" Old English wac "weak, pliant, soft," wician "to give way, yield," wice "wych elm," Old Norse vikja "to bend, turn," Swedish viker "willow twig, wand," German wechsel "change."