(of a wound or sore) become septic; suppurate: (as adjective festering)a festering abscess
(of food or rubbish) become rotten and offensive to the senses:piles of mouldy grey paper festered by the sink
(of a negative feeling or a problem) become worse or more intense, especially through long-term neglect or indifference:below the surface, the old antagonisms festered
(of a person) deteriorate physically and mentally in isolated inactivity:remand prisoners are left to fester in our jails while they wait for trial
