Source : Webster's Revised Unabridged Dictionary (1913)

Adjoin \Ad*join"\, v. t. [imp. & p. p. {Adjoined}; p. pr. & vb.
   n. {Adjoining}.] [OE. ajoinen, OF. ajoindre, F. adjoindre,
   fr. L. adjungere; ad + jungere to join. See {Join}, and cf.
   {Adjunct}.]
   To join or unite to; to lie contiguous to; to be in contact
   with; to attach; to append.

         Corrections . . . should be, as remarks, adjoined by
         way of note.                             --Watts.

Adjoining \Ad*join"ing\, a.
   Joining to; contiguous; adjacent; as, an adjoining room.
   ``The adjoining fane.'' --Dryden.

         Upon the hills adjoining to the city.    --Shak.

   Syn: Adjacent; contiguous; near; neighboring; abutting;
        bordering. See {Adjacent}.

Source : WordNet®

adjoining
     adj : having a common boundary or edge; touching; "abutting lots";
           "adjoining rooms"; "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:
           {abutting}, {adjacent}, {conterminous}, {contiguous}, {neighboring(a)}]