noun

• (alchemy) A liquid which converts lead to gold.
  "For Chinese alchemists, gold held the key to the Elixir, the Eastern equivalent of the Philosopher's Stone."
• (alchemy) A substance or liquid which is believed to cure all ills and give eternal life.
• (by extension) The alleged cure for all ailments; cure-all, panacea.
  "The silver-bullet cancer cures of yesterday’s newsmagazine covers, like interferon and angiogenesis inhibitors, disappointed the breathless expectations, as have elixirs such as antioxidants, Vioxx, and hormone replacement therapy."
• (pharmacy) A sweet flavored liquid (usually containing a small amount of alcohol) used in compounding medicines to be taken by mouth in order to mask an unpleasant taste.
  "The subcommittee's report to the Council on Pharmacy and Chemistry shows that the action of somnos is practically identical with that of a 5 per cent elixir of hydrated chloral."