The Collaborative International Dictionary of English v.0.48:

Confederate \Con*fed"er*ate\, v. t. [imp. & p. p.
   Confederated; p. pr. & vb. n. Confederating.]
   To unite in a league or confederacy; to ally.
   [1913 Webster]

         With these the Piercies them confederate. --Daniel.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Confederate \Con*fed"er*ate\, v. i.
   To unite in a league; to join in a mutual contract or
   covenant; to band together.
   [1913 Webster]

         By words men . . . covenant and confederate. --South.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Confederate \Con*fed"er*ate\, a. [L. confoederatus, p. p. of
   confoederare to join by a league; con- + foederare to
   establish by treaty or league, fr. foedus league, compact.
   See Federal.]
   1. United in a league; allied by treaty; engaged in a
      confederacy; banded together; allied.
      [1913 Webster]

            All the swords
            In Italy, and her confederate arms,
            Could not have made this peace.       --Shak.
      [1913 Webster]

   2. (Amer. Hist.) Of or pertaining to the government of the
      eleven Southern States of the United States which
      (1860-1865) attempted to establish an independent nation
      styled the Confederate States of America; as, the
      Confederate congress; Confederate money.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Confederate \Con*fed"er*ate\, n.
   1. One who is united with others in a league; a person or a
      nation engaged in a confederacy; an ally; also, an
      accomplice in a bad sense.
      [1913 Webster]

            He found some of his confederates in gaol.
                                                  --Macaulay.
      [1913 Webster]

   2. (Amer. Hist.) A name designating an adherent to the cause
      of the States which attempted to withdraw from the Union
      (1860-1865).
      [1913 Webster]

WordNet (r) 3.0 (2006):

Confederate
    adj 1: of or having to do with the southern Confederacy during
           the American Civil War; "Confederate soldiers"
    2: united in a confederacy or league [syn: allied,
       confederate, confederative]
    n 1: a supporter of the Confederate States of America
    2: someone who assists in a plot [syn: confederate,
       collaborator, henchman, partner in crime]
    3: a person who joins with another in carrying out some plan
       (especially an unethical or illegal plan) [syn: accomplice,
       confederate]
    v 1: form a group or unite; "The groups banded together" [syn:
         band together, confederate]
    2: form a confederation with; of nations