Synonyms for "Supremacy clause" include "federal supremacy," "preemption doctrine," "supremacy doctrine," "supremacy of federal law," and "federal preemption." These terms refer to the principle in the US Constitution that federal law takes precedence over state law in cases of conflict. This ensures that the federal government has the power to establish laws that apply uniformly across the country, without being overshadowed by state legislation. The Supremacy clause is a critical feature of the US government structure, and it's essential in promoting consistency and coherence in the law. Overall, these synonyms help to clarify the meaning and importance of the Supremacy clause in American law.