The Collaborative International Dictionary of English v.0.48:

Unite \U*nite"\, a. [L. unitus, p. p. See Unite, v. t.]
   United; joint; as, unite consent. [Obs.] --J. Webster.
   [1913 Webster]

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.
      [1913 Webster]

   Syn: To add; join; annex; attach. See Add.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Unite \U*nite"\, v. i.
   1. To become one; to be cemented or consolidated; to combine,
      as by adhesion or mixture; to coalesce; to grow together.
      [1913 Webster]

   2. To join in an act; to concur; to act in concert; as, all
      parties united in signing the petition.
      [1913 Webster]

WordNet (r) 3.0 (2006):

unite
    v 1: act in concert or unite in a common purpose or belief [syn:
         unite, unify] [ant: carve up, dissever, divide,
         separate, split, split up]
    2: become one; "Germany unified officially in 1990"; "the cells
       merge" [syn: unify, unite, merge] [ant: break apart,
       disunify]
    3: have or possess in combination; "she unites charm with a good
       business sense" [syn: unite, combine]
    4: be or become joined or united or linked; "The two streets
       connect to become a highway"; "Our paths joined"; "The
       travelers linked up again at the airport" [syn: connect,
       link, link up, join, unite]
    5: bring together for a common purpose or action or ideology or
       in a shared situation; "the Democratic Patry platform united
       several splinter groups" [syn: unite, unify]
    6: join or combine; "We merged our resources" [syn: unite,
       unify, merge]