A very qualitative term which includes any and all trace gases which have a greater oxidation potential than oxygen (for example, ozone, peroxyacetyl nitrate, hydrogen peroxide, organic peroxides,
NO3, etc.). It is recommended that alternative, more definitive terms be used which define the specific oxidant of interest whenever possible.
Source:
PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2204 (https://doi.org/10.1351/pac199062112167)