vendetta

This term carries a heavy connotation of obsession and cyclical violence. It describes a conflict where the primary motivation is not a specific goal or a legal resolution, but the act of retaliation itself, creating a self-perpetuating loop of revenge. While it can refer to ancestral blood feuds, in modern usage it often describes a targeted, personal crusade to destroy someone's reputation or career. It implies a level of persistence and bitterness that exceeds a simple disagreement or a temporary grudge.