The Collaborative International Dictionary of English v.0.48:

Unite \U*nite"\, v. t. [imp. & p. p. United; p. pr. & vb. n.
   Uniting.] [L. unitus, p. p. of unire to unite, from unus
   one. See One.]
   1. To put together so as to make one; to join, as two or more
      constituents, to form a whole; to combine; to connect; to
      join; to cause to adhere; as, to unite bricks by mortar;
      to unite iron bars by welding; to unite two armies.
      [1913 Webster]

   2. Hence, to join by a legal or moral bond, as families by
      marriage, nations by treaty, men by opinions; to join in
      interest, affection, fellowship, or the like; to cause to
      agree; to harmonize; to associate; to attach.
      [1913 Webster]

            Under his great vicegerent reign abide,
            United as one individual soul.        --Milton.
      [1913 Webster]

            The king proposed nothing more than to unite his
            kingdom in one form of worship.       --Clarendon.
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   Syn: To add; join; annex; attach. See Add.
        [1913 Webster]

WordNet (r) 3.0 (2006):

uniting
    n 1: the combination of two or more commercial companies [syn:
         amalgamation, merger, uniting]
    2: the act of making or becoming a single unit; "the union of
       opposing factions"; "he looked forward to the unification of
       his family for the holidays" [syn: union, unification,
       uniting, conjugation, jointure] [ant: disunion]