<p><strong>adjective</strong></p><ul><li>pertaining to or of the nature of a union of states under a central government distinct from the individual governments of the separate states, as in federal government</li><li>federal system of, relating to, or noting such a central government: federal offices</li><li>(initial capital letter) U.S. History: of or relating to the Federalists or to the Federalist party</li><li>supporting the principles of the Federalist party</li><li>(in the Civil War) pertaining to or supporting the Union government</li><li>relating to or adhering to the support of the Constitution</li><li>(initial capital letter) pertaining to or designating the styles of the decorative arts and architecture current in the U.S. from about 1780 to about 1830</li><li>of or relating to a compact or a league, especially a league between nations or states</li></ul><p><strong>noun</strong></p><ul><li>an advocate of federation or federalism</li><li>(initial capital letter) U.S. History: a Federalist</li><li>an adherent of the Union government during the Civil War; Unionist</li><li>a soldier in the Federal army</li></ul>