The Collaborative International Dictionary of English v.0.48:

Intercommon \In`ter*com"mon\, v. t. [imp. & p. p.
   Intercommoned; p. pr. & vb. n. Intercommoning.] [OF.
   entrecommuner. See Inter-, and Common, and cf.
   Intercommune.]
   [1913 Webster]
   1. To share with others; to participate; especially, to eat
      at the same table. [Obs.] --Bacon.
      [1913 Webster]

   2. (O. Eng. Law) To graze cattle promiscuously in the commons
      of each other, as the inhabitants of adjoining townships,
      manors, etc.
      [1913 Webster]

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

INTERCOMMONING, Eng. law. Where the commons of two manors lie together, and
the inhabitants, or those having a right of common of both, have time out of
mind depastured their cattle, without any distinction, this is called
intercommoning.