The Collaborative International Dictionary of English v.0.48:

neighbor \neigh"bor\, v. t. [imp. & p. p. Neighbored; p. pr. &
   vb. n Neighboring.]
   1. To adjoin; to border on; to be near to.
      [1913 Webster]

            Leisurely ascending hills that neighbor the shore.
                                                  --Sandys.
      [1913 Webster]

   2. To associate intimately with. [Obs.] --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Neighboring \Neigh"bor*ing\, a.
   Living or being near; adjacent; as, the neighboring nations
   or countries.
   [1913 Webster]

WordNet (r) 3.0 (2006):

neighboring
    adj 1: having a common boundary or edge; abutting; touching;
           "Rhode Island has two bordering states; Massachusetts and
           Conncecticut"; "the side of Germany conterminous with
           France"; "Utah and the contiguous state of Idaho";
           "neighboring cities" [syn: adjacent, conterminous,
           contiguous, neighboring(a)]

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "neighboring":
   abutting, adjacent, adjoining, ambient, bordering, circling,
   circumambient, circumferential, circumflex, circumfluent,
   circumfluous, circumjacent, close, close-by, connecting,
   conterminous, contiguous, coterminous, embracing, encircling,
   enclosing, encompassing, end to end, endways, endwise, enfolding,
   enveloping, environing, face to face, immediate, joined,
   juxtaposed, juxtapositional, juxtapositive, near, nearby, neighbor,
   next, peripheral, roundabout, suburban, surrounding, touching,
   wrapping