free radical

American  

noun

Chemistry, Biochemistry.

1. an atom or molecule that bears an unpaired electron and is extremely reactive, capable of engaging in rapid chain reactions that destabilize other molecules and generate many more free radicals: in the body, deactivated by antioxidants, uric acid, and certain enzyme activities.

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free radical British  

noun

1. Sometimes shortened to: radical. an atom or group of atoms containing at least one unpaired electron and existing for a brief period of time before reacting to produce a stable molecule Compare group

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free radical Scientific  

1. An atom or group of atoms that has at least one unpaired electron and is therefore unstable and highly reactive. In animal tissues, free radicals can damage cells and are believed to accelerate the progression of cancer, cardiovascular disease, and age-related diseases.

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Etymology

Origin of free radical

First recorded in 1895–1900

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Example Sentences

See Examples For:

free radical

That could indicate that the presence of other compounds in the body might dampen free radical creation.

From Los Angeles Times ● Oct. 17, 2026

Seaweed is valued for its antioxidant properties, which helps protect cells against free radical damage.

From Salon ● Aug. 5, 2024

Left unchecked, free radical activity damages cells and ultimately may result in skin aging and skin cancer.

From Science Daily ● Nov. 2, 2023

“He’s like a free radical, in some sense,” he continued, referring to how Mr. Petzold makes films outside the German film establishment.

From New York Times ● Jun. 3, 2023

"I always thought a free radical was a political bomb thrower out of jail."

From The Egyptian Cat Mystery by Harold L. (Harold Leland) Goodwin

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