free radical

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.

free radical

noun

1. 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 Sometimes shortened toradical Compare group

free radical

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.

Word History and Origins

Origin of free radical¹

First recorded in 1895–1900

Example Sentences

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

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

From Salon

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