Meaning

noun any substance that causes injury or illness or death of a living organism

noun anything that harms or destroys

verb spoil as if by poison

originFrom Middle English poysoun, poyson, pusoun, from Old French poison, poisun, from Latin pōtiōnem (“drink, a draught, a poisonous draught, a potion”), from pōtō (“to drink”). See also potion and potable (from the same root). Mostly displaced native Old English ātor. See more at atter.

Etymology from Wiktionary, CC BY-SA 3.0