adjective

1. of or formed by a compact; specif., designating or of a union of states, groups, etc. in which each member agrees to subordinate its governmental power to that of the central authority in certain specified common affairs
2. 1. designating, of, or having to do with a central authority or government in such a union
   2. ☆ designating, of, or having to do with the central government of the U.S.
3. ☆ of or supporting the Federalist Party or its principle of strong centralized government
4. ☆ of or pertaining to the style in architecture and furniture based on classical Roman models that flourished in the U.S. from 1780 into the 1830s
5. ☆ of or supporting the government of the U.S. in the Civil War; Union; pro-Union

Etymology: < L foedus (gen. foederis), a league, compact, treaty: see faith & -al

noun

1. ☆ a Federalist
2. ☆ a supporter or soldier of the U.S. government in the Civil War
3. ☆ a U.S. federal agent or officer