The term "persistent cruelty" is quite strong and can be difficult to describe using synonyms. Some possible alternatives might include words like "relentless brutality," "unyielding harshness," or "unwavering callousness." Other options could be "unrelenting meanness," "incessant malice," or "continual torment." Regardless of the phrasing, all of these synonyms suggest a sustained and ongoing pattern of mistreatment or aggression. It's a deeply concerning issue that demands attention and action, whether it takes the form of bullying in school, abuse in relationships, or systemic cruelty within a larger social or political system.