Nordhausen sulphuric acid, also known as fuming sulphuric acid or Nordhausen acid, is a highly corrosive and dangerous substance used in various industrial processes. Synonyms for this potent acid include "oleum", "vitriol oil", and "nordhausen oil", which all denote its acidic and caustic properties. Additionally, it is sometimes referred to as "fuming sulphuric acid" due to its characteristic release of pungent fumes when exposed to air. It is important to handle this powerful acid with extreme caution as it poses significant health risks and can cause severe burns, therefore proper safety measures should always be followed.