free radical


noun Chemistry, Biochemistry.

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.
Compare diradical.

Origin of free radical

First recorded in 1895–1900

British Dictionary definitions for free radical

free radical

noun

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 to: radical Compare group (def. 10)

Medical definitions for free radical

free radical

n.

An uncharged atom or group of atoms having at least one unpaired electron, which makes it highly reactive.
An organic compound having some unpaired valence electrons; a normal byproduct of oxidation reactions in metabolism.

Scientific definitions for free radical

free radical

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.