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

Oxidative stress is the imbalance between free radicals (reactive molecules that can damage cells and genetic material) and antioxidants in the body. —Lana Barhum, Verywell Health, 31 Oct. 2024

Meet free radicals: unstable oxygen molecules—generated by exposure to external factors like environmental pollution and UV rays—that damage cellular structures like DNA, lipids, and proteins. —Abby Dupes, StyleCaster, 20 Sep. 2024

They might be best known as antioxidants (which fend off cell-damaging molecules called free radicals), but newer research suggests they’re also fermented by your friendly gut bacteria, further supporting a healthy microbiome. —Erica Sloan, SELF, 4 Sep. 2024

Antioxidants—like curcumin—work by binding to and neutralizing free radicals, thus reducing the risk of cellular damage that can lead to disease. —Sarah Bence, Verywell Health, 28 Oct. 2024

Word History

First Known Use

1870, in the meaning defined above

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