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

ROS are a type of free radical, a broad term for one class of unstable, high-energy molecules.

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

The free radical generated from photochemistry comes into play here, entering the enzyme active site and engaging the enzymatic intermediate to enable new chemistry.

From Science Daily ● May 30, 2024

The odd number immediately tells us that we have a free radical, so we know that not every atom can have eight electrons in its valence shell.

From Textbooks ● Feb. 14, 2019

"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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