confederacy

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A union of persons, parties, or states; a league.
• noun The persons, parties, or states joined in such a union.
• noun The Confederate States of America.
• noun A group of people who have united for unlawful practices; a conspiracy.

from The Century Dictionary.

• noun A contract between two or more persons, bodies of men, or states, for mutual support or joint action of any kind; a compact, league, or alliance.
• noun An aggregation of persons, parties, states, or nations united by a league; a confederation.
• noun In law, a combination of two or more persons to commit an unlawful act; a conspiracy.
• noun Confederated action; coöperation; concurrence.

from the GNU version of the Collaborative International Dictionary of English.

• noun A league or compact between two or more persons, bodies of men, or states, for mutual support or common action; alliance.
• noun The persons, bodies, states, or nations united by a league; a confederation.
• noun (Law) A combination of two or more persons to commit an unlawful act, or to do a lawful act by unlawful means. See Conspiracy.
• noun (Amer. Hist.) With the, the Confederate States of America.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun an alliance

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the southern states that seceded from the United States in 1861
• noun a secret agreement between two or more people to perform an unlawful act
• noun a union of political organizations
• noun a group of conspirators banded together to achieve some harmful or illegal purpose