The term "Anti-Federalist" refers to a group of individuals in the late 18th century who opposed the ratification of the U.S. Constitution. They believed that the new Constitution would create a strong central government that could threaten individual liberties and the rights of states. Anti-Federalists argued for a more decentralized government structure, emphasizing the importance of local control and individual freedoms. Key figures among the Anti-Federalists included Patrick Henry and George Mason, who voiced their concerns during the debates surrounding the Constitution. Their opposition led to the inclusion of the Bill of Rights, which aimed to protect individual freedoms and limit government power, addressing some of their main concerns.