The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

         Corrections . . . should be, as remarks, adjoined by
         way of note.                             --Watts.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Adjoin \Ad*join"\ ([a^]d*join"), v. i.
   1. To lie or be next, or in contact; to be contiguous; as,
      the houses adjoin.
      [1913 Webster]

            When one man's land adjoins to another's.
                                                  --Blackstone.
      [1913 Webster]

   Note: The construction with to, on, or with is obsolete or
         obsolescent.
         [1913 Webster]

   2. To join one's self. [Obs.]
      [1913 Webster]

            She lightly unto him adjoined side to side.
                                                  --Spenser.
      [1913 Webster]

WordNet (r) 3.0 (2006):

adjoin
    v 1: lie adjacent to another or share a boundary; "Canada
         adjoins the U.S."; "England marches with Scotland" [syn:
         border, adjoin, edge, abut, march, butt, butt
         against, butt on]
    2: be in direct physical contact with; make contact; "The two
       buildings touch"; "Their hands touched"; "The wire must not
       contact the metal cover"; "The surfaces contact at this
       point" [syn: touch, adjoin, meet, contact]
    3: attach or add; "I adjoin a copy of your my lawyer's letter"