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
Words nearby free radical
free on board,
free on rail,
free perspective,
free port,
free press,
free radical,
free reach,
free reaching,
free recall,
free rein,
free ride
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.