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

Example Sentences

Scientists at Weill Cornell Medicine have identified a surprising culprit that may contribute to dementia: free radicals generated in a particular region of brain support cells known as astrocytes.

From Science Daily

The free radical species generated, hydroxyl radical, is extremely reactive and hits DNA like a shotgun blast, causing damage everywhere, Burrows said.

From Science Daily

However, even though it is necessary to maintain cell functions, oxygen also causes oxidative stress by forming free radicals, reactive molecules that endanger the cell.

From Science Daily

Antioxidants neutralize free radicals, which are unstable molecules that harm our cells.

From Salon

“Radiation forms free radicals on the surface, and they react with oxygen inside the space station, creating a metallic smell,” she says.

From BBC