free radical

https://doi.org/10.1351/goldbook.F02519
See:
radical (free radical)
Sources:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2190 [Terms] [Paper]
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1116 [Terms] [Paper]