free radical

noun

: 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

Examples of free radical in a Sentence

Recent Examples on the Web Fueled by exposure to air, light, and heat, unsaturated fats break down and release free radicals. Ali Francis, Bon Appétit, 12 Mar. 2024 Several studies show that vitamin C protects and improves skin, helping neutralize free radicals that cause oxidative skin stress, leading to premature aging and reducing the appearance of fine lines and wrinkles. Kate Donnelly, Forbes, 29 Feb. 2024 Antioxidants help neutralize the free radicals in our bodies which, when imbalanced, can cause cell damage and lead to disease. Clare Mulroy, USA TODAY, 16 Jan. 2024 Vitamin E Vitamin E protects against damage from free radicals and clots and aids in immune function. Allison Futterman, Discover Magazine, 16 Feb. 2024 Oils like apricot kernel, raspberry seed, and rosehip soothe, smoothe, promote cell regeneration, and protect lips from free radicals, all while giving you a semi-pigmented sheen that’s long lasting. Stephanie Osmanski, Southern Living, 14 Feb. 2024 So the scientists exposed the tardigrades to different kinds of molecules known to block cysteine oxidation, as scientists call binding by a free radical. Meghan Bartels, Scientific American, 17 Jan. 2024 The vegan formula also contains antioxidants to protect from free radical damage and squalane to hydrate throughout the day. Jackie Fields, Peoplemag, 20 Feb. 2024 The survival mechanism kicks off when cysteines, one of the amino acids that forms proteins in the body, come into contact with these oxygen free radicals and becomes oxidized, the researchers found. Jenna Schnuer, CNN, 5 Feb. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'free radical.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1870, in the meaning defined above

Time Traveler
The first known use of free radical was in 1870

Dictionary Entries Near free radical

Cite this Entry

“Free radical.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/free%20radical. Accessed 29 Mar. 2024.

Medical Definition

free radical

noun
: 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

More from Merriam-Webster on free radical

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!