Free radical

a radical in its (usually transient) uncombined state; an atom or atom group carrying an unpaired electron and no charge

Description
Free radicals may be involved as short-lived, highly active intermediates in various reactions in living tissue, notably in photosynthesis. Oxygen free radicals mediated my iron atoms, play an important role in oxidative stess in iron overloaded patients. The free radical nitric oxide, NO·, plays an important role in vasodilation. Syn radical (4)