noun

1. a substance sought by medieval alchemists because it was thought to have the power to change base metals into gold or (in full elixir of life) to prolong life indefinitely
2. Rare the quintessence; underlying principle
3. a supposed remedy for all ailments; panacea
4. Pharmacy a sweetened, aromatic solution used as a vehicle for a medicine or alcohol, or as a nonmedicated flavoring

Etymology: ME < ML < Ar al-iksīr < al, the + iksīr, philosopher's stone, prob. < Gr xērion, powder for drying wounds < xēros, dry: see xero-