free radical

noun

|Updated on: 29 Jul 2018

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

Recent Examples of free radical from the Web

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
For a video about free radicals and antioxidants, take a look at my YouTube channel, www.youtube.com/user/BaumannCosmetic or follow Baumann Cosmetic on Facebook.

— dr. leslie baumann, miamiherald, "Why antioxidants are so important for beautiful, healthy skin | Miami Herald," 19 Mar. 2018
Stevia is a natural antioxidant, helping your body fight against free radicals (molecules that can damage cells, lead to heart disease and cancer, as well as other illnesses).

— the editors of organic life, Good Housekeeping, "How To Grow Your Own Natural Stevia Right In Your Garden," 8 Aug. 2017

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.

First Known Use of free radical

1870

in the meaning defined above

See Words from the same year

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Medical Dictionary

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