The Collaborative International Dictionary of English v.0.48:

Confederacy \Con*fed"er*a*cy\, n. (Amer. Hist.)
   With the, the Confederate States of America.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Confederacy \Con*fed"er*a*cy\, n.; pl. Confederacies. [From
   Confederate, a.]
   1. A league or compact between two or more persons, bodies of
      men, or states, for mutual support or common action;
      alliance.
      [1913 Webster]

            The friendships of the world are oft
            Confederacies in vice or leagues of pleasure.
                                                  --Addison.
      [1913 Webster]

            He hath heard of our confederacy.     --Shak.
      [1913 Webster]

            Virginia promoted a confederacy.      --Bancroft.
      [1913 Webster]

   2. The persons, bodies, states, or nations united by a
      league; a confederation.
      [1913 Webster]

            The Grecian common wealth, . . . the most heroic
            confederacy that ever existed.        --Harris.
      [1913 Webster]

            Virgil has a whole confederacy against him.
                                                  --Dryden.
      [1913 Webster]

   3. (Law) A combination of two or more persons to commit an
      unlawful act, or to do a lawful act by unlawful means. See
      Conspiracy.

   Syn: League; compact; alliance; association; union;
        combination; confederation.
        [1913 Webster]

WordNet (r) 3.0 (2006):

Confederacy
    n 1: the southern states that seceded from the United States in
         1861 [syn: Confederacy, Confederate States,
         Confederate States of America, South, Dixie,
         Dixieland]
    2: a union of political organizations [syn: confederation,
       confederacy, federation]
    3: a group of conspirators banded together to achieve some
       harmful or illegal purpose [syn: conspiracy, confederacy]
    4: a secret agreement between two or more people to perform an
       unlawful act [syn: conspiracy, confederacy]

Moby Thesaurus II by Grady Ward, 1.0:

134 Moby Thesaurus words for "confederacy":
   Anschluss, Bund, Rochdale cooperative, addition, affiliation,
   agglomeration, aggregation, agreement, alignment, alliance,
   amalgamation, anschluss, artifice, assemblage, assimilation,
   association, axis, band, blend, blending, bloc, body, cabal,
   cahoots, cartel, centralization, coadunation, coalescence,
   coalition, colleagueship, college, collegialism, collegiality,
   collusion, combination, combine, combo, common market, complicity,
   complot, composition, comradeship, confederation, confraternity,
   congeries, conglomeration, conjugation, conjunction, connivance,
   consolidation, conspiracy, consumer cooperative, contrivance,
   contriving, cooperative, cooperative society, copartnership,
   copartnery, corps, council, counterplot, covin, credit union,
   customs union, deep-laid plot, economic community, ecumenism,
   embodiment, encompassment, engineering, enosis, federalization,
   federation, fellowship, finagling, finesse, frame-up, fraternalism,
   fraternity, fraternization, free trade area, freemasonry, fusion,
   game, gang, group, grouping, hookup, inclusion, incorporation,
   integration, intrigue, junction, junta, league, little game,
   machination, machine, maneuvering, manipulation, marriage, meld,
   melding, merger, mob, package, package deal, partnership, plot,
   plotting, political machine, rigging, ring, scheme, schemery,
   scheming, society, sodality, solidification, sorority, stratagem,
   syncretism, syndication, syneresis, synthesis, tie-in, tie-up,
   trick, underplot, unification, union, web of intrigue, wedding,
   wire-pulling



Bouvier's Law Dictionary, Revised 6th Ed (1856):

CONFEDERACY, equity pleading. The fourth part of a bill in chancery usually
charges a confederacy; this is either general or special.
     2. The first is by alleging a general charge of confederacy between the
defendants and other persons to injure or defraud the plaintiff. The common
form of the charge is, that the defendants, combining and confederating
together, to and with divers other persons as yet to the plaintiff unknown,
but whose names, when discovered, he prays may be inserted in the bill, and
they be made parties thereto, with proper and apt words to charge them with
the premises, in order to injure and oppress the plaintiff in ti e premises,
do absolutely refuse, &c. Mitf. Eq. Pl. by Jeremy, 40; Coop. Eq. Pl. 9
Story, Eq. Pl. Sec. 29; 1 Mont. Eq. Pl. 77; Barton, Suit in Eq. 33; Van
Heyth. Eq. Drafts, 4.
     3. When it is intended to rely on a confederacy or combination as a
ground of equitable jurisdiction, the confederacy must be specially charged
to justify an assumption of jurisdiction. Mitf. Eq. Pl. by Jeremy, 41;
Story, Eq. Pl. Sec. 30.
     4. A general allegation of confederacy is now considered as mere form.
Story, Eq. Pl. Sec. 29; 4 Bouv. Inst. n. 4169.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

CONFEDERACY, intern. law. An agreement between two or more states or
nations, by which they unite for their mutual protection and good. This term
is applied to such agreement between two independent nations, but it is used
to signify the union of different states of the same nation, as the
confederacy of the states.
     2. The original thirteen states, in 1781, adopted for their federal
government the "Articles of confederation and perpetual union between the
States," which continued in force until the present constitution of the
United States went into full operation, on the 30th day of April, 1789, when
president Washington was sworn into office. Vide 1 Story on the Const. B. 2,
c. 3 and 4.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

CONFEDERACY, crim. law. An agreement between two or more persons to do an
unlawful act, or an act, which though not unlawful in itself, becomes so by
the confederacy. The technical term usually employed to signify this
offence, is conspiracy. (q.v.)