free radical

noun

: an especially reactive atom or group of atoms that has one or more unpaired electrons

especially : one that is produced in the body by natural biological processes or introduced from an outside source (such as tobacco smoke, toxins, or pollutants) and that can damage cells, proteins, and DNA by altering their chemical structure

Examples of free radical in a Sentence

Recent Examples on the Web

Green tea, resveratrol and a proprietary turmeric extract protect against free radicals. —Bestreviews, Chicago Tribune, 16 June 2025

Meanwhile, bisabolol provides additional soothing benefits as well as protection from free radical damage. —Conçetta Ciarlo, Vogue, 13 June 2025

Antioxidants counter destructive free radical molecules in cells. —Lana Barhum, Verywell Health, 9 June 2025

This vitamin can also boost your skin health by reducing collagen breakdown and neutralizing the effect of free radical damage on the skin. —Bestreviews, Mercury News, 13 May 2025

Word History

First Known Use

1870, in the meaning defined above

Rhymes for free radical

• radicle

Medical Definition

free radical

noun

: an especially reactive atom or group of atoms that has one or more unpaired electrons

especially : one that is produced in the body by natural biological processes or introduced from outside (as in tobacco smoke, toxins, or pollutants) and that can damage cells, proteins, and DNA by altering their chemical structure