The Collaborative International Dictionary of English v.0.48:

Anastomose \A*nas"to*mose\, v. i. [imp. & p. p. Anastomozed;
   p. pr. & vb. n. Anastomosing.] [Cf. F. anastomoser, fr.
   anastomose. See Anastomosis.]
   1. (Anat. & Bot.) To inosculate; to intercommunicate by
      anastomosis, as the arteries and veins.
      [1913 Webster]

            The ribbing of the leaf, and the anastomosing
            network of its vessels.               --I. Taylor.
      [1913 Webster]

   2. Of any channels or lines, to meet and unite or run into
      each other, as rivers; to coalesce; to interjoin.
      [Webster 1913 Suppl.]