"Organic radical" is a term commonly used in chemistry to refer to an atom or a group of atoms that contains an unpaired electron. Synonyms for organic radical include free radical, radical species, and radical molecule. Free radicals are highly reactive entities that play important roles in chemical reactions, natural processes, and biological systems. Radical species are characterized by their high instability, low selectivity, and potential for damage to cell membranes and DNA. The term radical molecule is often used to describe organic compounds that contain one or more free radical atoms within their molecular structures. Examples of radical molecules include nitric oxide, superoxide, and hydroxyl radical.