festering

adjective

fes·ter·ing | \ ˈfe-st(ə-)riŋ

Definition of festering

1 : contaminated by an infective agent (such as a bacterium) and producing pus a festering wound But if the patient can manage it, the whirlpool is a dandy way to handle festering bedsores.— Paul G. Donohue

2a : persisting and growing increasingly bitter over time festering resentment … comedy that comes from a pit of festering hatred …— Robert Brustein

b : persistently producing bad or unhealthy effects Four hundred yards to the west, between the schoolhouse and the mountain, lay a festering center of sin, a bootleg whiskey still operated by the celebrated anti-Prohibition guerilla Sam Reever.— Russell Baker