c. 1300, pocioun "medicinal drink," from Old French pocion "potion, draught, medicine" (12c.), from Latin potionem (nominative potio) "a potion, a drinking," also "poisonous draught, magic potion," from potus, irregular past participle of potare "to drink," from PIE root *po(i)- "to drink." A doublet of poison (n.). Potus as a past-participle adjective in Latin meant "drunken."
