Middle English: from Old French, from Latin potio(n-) 'drink, poisonous draught', related to potare 'to drink'.

• poison from Middle English:

  A poison does not necessarily need to be in liquid form, but in early use the word meant a drink or medicine, specifically a potion with a harmful or dangerous ingredient. The source was Old French poison ‘magic potion’, from Latin potio, also the source of potion (Middle English). The saying one man's meat is another man's poison has been around for centuries and was being described as long ago as 1604 as ‘that old moth-eaten proverb’. A similar idea is found in the work of the Roman poet and philosopher Lucretius (c.94–55 bc): ‘What is food to one person may be bitter poison to others.’ A chalice (Middle English) from Latin calix, ‘cup’, also the source of the botanical calix) is a large cup or goblet, and a poisoned chalice something that seems attractive but is likely to be a source of problems. A poisoned chalice features in Shakespeare's Macbeth, and is the source of our expression.