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

By donating electrons to free radicals to stabilize them, vitamin C can neutralize their effects, thus delaying the breakdown of collagen for smoother, firmer skin. —Jenny Berg, Allure, 24 Jan. 2025

Its anthocyanins are more effective at scavenging free radicals than other antioxidants like vitamin E, quercetin, and catechin.30 A 100-gram (3.5-ounce) serving of purple corn also provides 2.5 grams of fiber (9% of the DV).31 12. —Johna Burdeos, Health, 23 Jan. 2025

Berries Berries are rich in flavonoids and plant chemicals, which have antioxidant and anti-inflammatory properties and can protect brain cells against oxidative stress (damage due to unstable molecules called free radicals outbalancing helpful antioxidants). —Sohaib Imtiaz, Verywell Health, 22 Jan. 2025

Flavonoids also help to regulate cellular activity and negate oxidative damage caused by the free radicals we’re exposed to daily. —Georgia Day, Vogue, 19 Jan. 2025

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