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.
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1083 (https://doi.org/10.1351/pac199466051077)