strychnine
Concise Oxford English Dictionary © 2008 Oxford University Press:
strychnine /ˈstrɪkniːn, -ɪn/
▶noun a bitter and highly poisonous alkaloid obtained from nux vomica and related plants.
– origin C19: from Fr., via L. from Gk strukhnos, denoting a kind of nightshade.
'strychnine' also found in these Oxford entries:

