Brønsted acid
A molecular entity capable of donating a hydron (proton) to a base, (i.e. a 'hydron donor') or the corresponding chemical species. For example: H2O, H3O+, CH3CO2H, H2SO4, HSO4, HCl, CH3OH, NH3.
See also: conjugate acid–base pair
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1091 (