Also contains definitions of: magic acid, superbase
A medium having a high acidity, generally greater than that of 100 wt.% sulfuric acid. The common superacids are made by dissolving a powerful Lewis acid (e.g. SbF5) in a suitable Brønsted acid such as HF or HSO3F. (An equimolar mixture of HSO3F and SbF5 is known by the trade name 'magic acid'.) In a biochemical context 'superacid catalysis' is sometimes used to denote catalysis by metal ions analogous to catalysis by hydrogen ions. By analogy, a compound having a very high basicity, such as lithium diisopropylamide, is called a 'superbase'.
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1169 (