Source : Webster's Revised Unabridged Dictionary (1913)

Adjacence \Ad"ja"cence\, Adjacency \Ad*ja"cen*cy\, [Cf. LL.
   adjacentia.]
   1. The state of being adjacent or contiguous; contiguity; as,
      the adjacency of lands or buildings.

   2. That which is adjacent. [R.] --Sir T. Browne.

Source : WordNet®

adjacency
     n : the attribute of being so near as to be touching [syn: {contiguity},
          {contiguousness}]

Source : Free On-Line Dictionary of Computing

adjacency
     
         A relationship between two {network} devices,
        e.g. {routers}, which are connected by one media segment so
        that a packet sent by one can reach the other without going
        through another network device.  The concept of adjacency is
        important in the exchange of routing information.
     
        Adjacent {SNA} {nodes} are nodes connected to a given node
        with no intervening nodes.  In {DECnet} and {OSI}, adjacent
        nodes share a common segment ({Ethernet}, {FDDI}, {Token
        Ring}).
     
        (1998-03-10)