"Must not go unpunished" is a phrase that conveys the principle of justice and accountability. It implies that when a wrongdoing has been committed, the offender must be held responsible for their actions, and punishment is necessary to ensure that the offense is not repeated. Some synonyms for "must not go unpunished" include "should be held accountable," "ought to face consequences," "deserves retribution," "must be punished," and "cannot be excused." These phrases reflect the importance of justice and provide a powerful reminder that wrongdoing cannot be ignored. So next time when you need to emphasize on the importance of accountability, choose your synonyms wisely!