free radical

noun

|Updated on: 17 Jun 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

In this way, vitamin C can do double-duty for your skin by eliminating the free radicals that can cause lines, wrinkles, and discoloration and by boosting collagen production for a smoother, more youthful look and feel to your skin.

— dr. leslie baumann, miamiherald, "Improving your diet can also improve your skin | Miami Herald," 22 Jan. 2018
Antioxidants provide cell protection from damage caused by free radicals.

— allison horton, miamiherald, "Want to reduce your odds of getting cancer? Stay active, lose weight and eat healthy | Miami Herald," 25 May 2018
Antioxidants protect against free radical damage, which is a form of oxidative stress that amplifies aging effects on both the body (wrinkles, heart disease) and mind (Alzheimer’s).

— sophie dodd, PEOPLE.com, "5 Ways Wine Can Be Good for Your Health," 25 May 2018
Blueberries are among the top antioxidant-rich fruits and vegetables, packed with phytochemicals that protect our cells from damage by free radicals, compounds that are linked to cancer and aging.

— molly kimball, NOLA.com, "Why you should eat blueberries every day (or at least regularly)," 15 May 2018
About 43 percent of the flavors were associated with significantly higher free radical levels while a few corresponded to lower levels.

— rita giordano, Philly.com, "How safe is the flavor you're vaping?," 17 Apr. 2018
Antioxidants deter the formation of cancer-causing free radicals.

— the editors of organic life, Good Housekeeping, "How (And Why) To Grow And Eat More Beets," 18 Apr. 2017
Antioxidants: Molecules that protect cells in your body from being damaged by free radicals (see definition below).

— theresa o'rourke, Redbook, "The Anti-Aging Plan for Your Exact Skin Tone," 15 Sep. 2011
Chronic inflammation also is implicated in causing the tangle of amyloid plaques associated with Alzheimer’s disease, and rogue inflammatory cells produce free radicals that cause genetic mutations leading to cancer and feed the growth of tumors.

— Houston Chronicle, "YouDocs0514," 13 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.

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