vetch n.

trailing evergreen plant with starry flowers, c. 1500, from Middle English pervinkle (early 14c. as a surname), a diminutive of parvink, pervink (12c.), which is from Old English perwince, pervince, from Late Latin pervinca "periwinkle," which is perhaps from Latin pervincire "to entwine, bind," from per "thoroughly" (see per) + vincire "to bind, fetter" (see wind (v.1)). Altered by association with words in peri-. In Middle English it was figurative of beauty, also a paragon, but also evil.

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."