'wolfsbane' originates from Old English, specifically the word 'wulfesbana', where 'wulf' meant 'wolf' and 'bana' meant 'slayer'.

'wulfesbana' transformed into the Middle English word 'wolfsbane', and eventually became the modern English word 'wolfsbane'.

Initially, it meant 'wolf slayer', referring to its use in poisoning wolves, but over time it evolved into its current meaning of a poisonous plant.