free radical

noun

Definition of free radical

: 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

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Loquat leaf delivers antioxidants, which both prevent sun damage in real time (by neutralizing free radicals) and repair skin overnight, while Japanese wild rose smooths skin texture and minimizes the look of my otherwise gigantic pores. — Deanna Pai, Condé Nast Traveler, "The Multitasking Sunscreen I Never Leave Home Without," 22 July 2019 Overtime, free radical oxidation can cause your skin's natural barrier to weaken. — Audrey Noble, Harper's BAZAAR, "3 Reasons Why Your Skin Routine Needs Vitamin E," 20 June 2019 Watermelon also contains lycopene, which is an antioxidant that destroys free radicals and reduces inflammation. — Heloise, Washington Post, "Hints From Heloise: Box of broth makes this dish great!," 19 June 2019 An atom that becomes separated from a larger chemical structure is called a free radical. — Kyle Smith, National Review, "The Millennial Who Rejects Hipness and Irony," 14 June 2019 Polluted air contains a host of tiny particles, like dirt and sulfur dioxide, that create free radicals on skin. — Nikki Krecicki, Allure, "7 Reasons Your Skin Looks Dull — and How to Get a Glowing Complexion," 8 June 2019 That both fuels your cells to proliferate and allows your body to absorb and neutralize more free radicals. — A.a. Newton, SELF, "Here’s What Niacinamide Can—and Can’t—Do for Your Skin," 8 May 2019 Antioxidants neutralize those free radicals to protect your skin from damage. — Chloe Metzger, Marie Claire, "What Do Antioxidants Really Do for Your Skin?," 20 July 2018 The vitamin C serum is packed with its namesake ingredient, as well as antioxidants to protect your skin from free radicals. — Meagan Fredette, Teen Vogue, "Does KylieSkin Care Live Up To The Hype?," 22 May 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'free radical.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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12 Aug 2019

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The first known use of free radical was in 1870

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free radical

noun

Medical Definition of free radical

: 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