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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Tim Calver © Tim Calver Bleaching occurs when water temperatures rise and the algae that live inside the coral, which photosynthesize and produce food for the corals, instead produce free radicals that are toxic, Baker said. — Jenny Staletovich, miamiherald, "Reefs are dying. Miami scientists hope lab-bred ‘super corals’ can help revive them | Miami Herald," 2 Mar. 2018 Alcohol creates free radicals and ups inflammation. — Krista Bennett Demaio, Cosmopolitan, "9 Beauty Fails That Mess With Your Skin (and How to Fix Them)," 2 Jan. 2015 Inflammation throughout your body turns on enzymes that break down collagen and leads to the production of free radicals, which can damage cells. — Dr. Melina Jampolis, CNN, "Aging gracefully: Tightening your skin safely and effectively," 16 May 2018 Thankfully, the body has a way of coping with free radicals by producing antioxidants. — Bryant Stamford, The Courier-Journal, "Free radicals, antioxidants and why you should maybe drink more red wine," 5 Apr. 2018 White blood cells produce free radicals from oxygen to kill bacteria or viruses, explains Linwei Tian, an environmental epidemiologist at the University of Hong Kong. — Marian Liu, CNN, "How your skin care could protect you from pollution," 20 Mar. 2018 Bio-Oil contains vitamin A, which helps boost collagen production, and vitamin E, which protects the skin against the effects of free radicals that can weaken and damage skin. — Emily Rekstis, SELF, "9 Ways to Use Bio-Oil, the Drugstore Scar Treatment People Love," 22 June 2018 The most important thing is to protect yourself against free radicals (basically all the bad stuff your skin comes in contact with every day that can cause damage on a molecular level). — Barret Wertz, GQ, "The Best Anti-Pollution Skincare Treatments Every Guy Should Try This Summer," 14 May 2018 Indeed, so much more is taken into account, including sebum production, exposure to free radicals and proclivity for damage. — Rebecca Norris, Allure, "Here's What Happened When I Tried a Fully Customized Hair-Care Regimen," 9 May 2018

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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26 Aug 2018

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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