Aqua regia is a highly corrosive mixture of nitric acid and hydrochloric acid, commonly used in metallurgy to dissolve noble metals like gold and platinum. Other synonyms for aqua regia include "king's water," "nitro-hydrochloric acid," and "spirit of salt." Aqua regia is also sometimes referred to as "apex acid," "regalis acid," and "corrosive water." Despite its dangerous properties, aqua regia has been used for centuries in various fields, such as chemistry, alchemy, and even warfare. Today, it remains an important tool for certain applications in science and industry.