What is the X in X-mas?
mid-13c., from Medieval Latin elixir "philosopher's stone," believed by alchemists to transmute baser metals into gold and/or to cure diseases and prolong life, from Arabic al-iksir, probably from late Greek xerion "powder for drying wounds," from xeros "dry" (see xerasia). General sense of "strong tonic" is 1590s; used for quack medicines from at least 1630s.
elixir e·lix·ir (ĭ-lĭk'sər)
A sweetened aromatic solution of alcohol and water, serving as a vehicle for medicine.
in alchemy, substance thought to be capable of changing base metals into gold. The same term, more fully elixir vitae, "elixir of life," was given to the substance that would indefinitely prolong life-a liquid that was believed to be allied with the philosopher's stone. Chinese Taoists not only sought the "pill of immortality" but developed techniques (meditation, breathing exercises, diet) that were thought to confer immortality by internal alchemy.