‘炼丹’ literally means 'to refine/forge elixirs' and refers to the ancient Daoist practice of creating medicinal or immortalizing elixirs—often using minerals like cinnabar, mercury, and lead—through heating, mixing, and repeated purification in furnaces. The character 炼 (liàn) conveys 'to refine, smelt, or purify through sustained effort', while 丹 (dān) originally meant 'cinnabar' (a red mineral), later symbolizing the perfected elixir itself or the ultimate goal of spiritual immortality.

This term belongs to classical Chinese religious and philosophical vocabulary and appears mainly in historical texts, literature, and discussions of traditional Chinese cosmology. Though no longer practiced literally today, it survives idiomatically (e.g., in phrases like 炼丹炉 'elixir furnace') and metaphorically—to describe arduous, transformative processes requiring patience and precision. It carries strong cultural resonance with Daoist immortality quests and early Chinese chemistry.