The Collaborative International Dictionary of English v.0.48:

Consociate \Con*so"ci*ate\, v. i.
   1. To be allied, confederated, or associated; to coalescence.
      [R.] --Bentley.
      [1913 Webster]

   2. To form an ecclesiastical consociation. [U.S.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Consociate \Con*so"ci*ate\, n. [L. consociatus, p. p. of
   consociare to associate, unite; con- + sociare to join,
   unite. See Social.]
   An associate; an accomplice. [Archaic] "Wicked consociates."
   --Bp. Hall.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Consociate \Con*so"ci*ate\, v. t. [imp. & p. p. Consociated;
   p. pr. & vb. n. Consociating.]
   1. To bring into alliance, confederacy, or relationship; to
      bring together; to join; to unite. [R.]
      [1913 Webster]

            Join pole to pole, consociate severed worlds.
                                                  --Mallet.
      [1913 Webster]

   2. To unite in an ecclesiastical consociation. [U.S.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

consociate
    v 1: bring or come into association or action; "The churches
         consociated to fight their dissolution" [syn: consociate,
         associate]