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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If left unchecked, chronic inflammation can lead to signs of skin aging by creating free radicals that scavenge electrons from healthy cells, therefore rendering them unstable. — Dr. Leslie Baumann, miamiherald, "Improving your diet can also improve your skin | Miami Herald," 22 Jan. 2018 Much like the sun causes skin cancer, the damage from UV rays can cause the creation of destructive molecules within the body, called free radicals, Khan explains. — Macaela Mackenzie, Allure, "The Scary Way Blue Light From Your Phone Can Affect Your Eyes and Vision," 6 July 2018 Research published in the Journal of Nutrition found that a zinc deficiency in rats led to impairments in DNA repair caused by free radicals, which can speed the aging process. — Amy Capetta, Woman's Day, "5 Anti-Aging Supplements That May Actually Work," 16 Oct. 2018 Like other berries, açaí are packed with antioxidants that can help build up your immune system and protect your cells against damage from free radicals. — Tehrene Firman, Good Housekeeping, "10 Things You Should Know About Açaí Berries, Nature's "Purple Gold"," 23 July 2018 Antioxidants are responsible for keeping your body and skin protected from harmful free radicals — unstable molecules that can cause your skin to age faster and potentially lead to skin cancer and other health issues. — Dr. Leslie Baumann, miamiherald, "Five antioxidant-rich foods to pile on your plate for better skin | Miami Herald," 2 Apr. 2018 During the process, free radicals and singlet oxygen are also formed and can inflict damage on cellular membranes, organelles, and proteins. — Lindsey Murray, Good Housekeeping, "[UPDATED] Woman Claims She Received Horrific Burns After Using Essential Oils," 28 Apr. 2017 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

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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14 Jan 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