A
chemical species that behaves both as an acid and as a base is called amphoteric. This property depends
upon the medium in which the species is investigated:
H2SO4
is an acid when studied in water, but becomes amphoteric in
superacids.
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1083