Most of us who have heard of it only know the bezoar as a tiny antidote stone from Harry Potter. Well, it's an actual thing! An intestinal blockage occurring in the stomachs of goats, and in special cases, humans, a bezoar was believed by alchemists in the Middle Ages to possess curative properties, which is definitely where J.K. Rowling got the idea from. Because of this, it (probably through French) comes from the Arabic word for "antidote", bazahr. This derives from Proto-Indo-European pad-zahr, literally "counter-poison", with pad meaning "against" or "counter" and zahr meaning "poison". The former is from Old Persian pa, which meant "protect" and comes from PIE peh, with the same meaning. The second is from Old Iranian jathra, which meant "to kill" (not that big of a transition), from PIE gwhen, "to strike" or still "kill". So a bezoar means "protecting [from a] kill", and J.K. Rowling knows her Middle Ages superstitions!
Adam Aleksic, a freshman studying linguistics at Harvard University, has been described as the internet's sixth most famous etymologist. He has disturbing interests in words, vexillology, geography, board games, limericks, and law, and he loves writing about himself in the third person.
The Etymology Nerd