A term embracing electromagnetic waves as well as fast moving particles. In radioanalytical chemistry the term usually refers to radiation emitted during a nuclear process (radioactive decay, nuclear reaction, nuclear fission, accelerators).
Source:
PAC, 1994, 66, 2513. 'Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)' on page 2523 (https://doi.org/10.1351/pac199466122513)