The Collaborative International Dictionary of English v.0.48:

Accompany \Ac*com"pa*ny\, v. i.
   1. To associate in a company; to keep company. [Obs.]
      --Bacon.
      [1913 Webster]

            Men say that they will drive away one another, . . .
            and not accompany together.           --Holland.
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   2. To cohabit (with). [Obs.] --Milton.
      [1913 Webster]

   3. (Mus.) To perform an accompanying part or parts in a
      composition.
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The Collaborative International Dictionary of English v.0.48:

Accompany \Ac*com"pa*ny\, v. t. [imp. & p. p. Accompanied; p.
   pr. & vb. n. Accompanying] [OF. aacompaignier, F.
   accompagner, to associate with, fr. OF. compaign, compain,
   companion. See Company.]
   1. To go with or attend as a companion or associate; to keep
      company with; to go along with; -- followed by with or by;
      as, he accompanied his speech with a bow.
      [1913 Webster]

            The Persian dames, . . .
            In sumptuous cars, accompanied his march. --Glover.
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            They are never alone that are accompanied with noble
            thoughts.                             --Sir P.
                                                  Sidney.
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            He was accompanied by two carts filled with wounded
            rebels.                               --Macaulay.
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   2. To cohabit with. [Obs.] --Sir T. Herbert.
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   Syn: To attend; escort; go with.

   Usage: To Accompany, Attend, Escort. We accompany those
          with whom we go as companions. The word imports an
          equality of station. We attend those whom we wait upon
          or follow. The word conveys an idea of subordination.
          We escort those whom we attend with a view to guard
          and protect. A gentleman accompanies a friend to some
          public place; he attends or escorts a lady.
          [1913 Webster]

WordNet (r) 3.0 (2006):

accompany
    v 1: be present or associated with an event or entity; "French
         fries come with the hamburger"; "heart attacks are
         accompanied by distruction of heart tissue"; "fish usually
         goes with white wine"; "this kind of vein accompanies
         certain arteries" [syn: attach to, accompany, come
         with, go with]
    2: go or travel along with; "The nurse accompanied the old lady
       everywhere"
    3: perform an accompaniment to; "The orchestra could barely
       follow the frequent pitch changes of the soprano" [syn: play
       along, accompany, follow]
    4: be a companion to somebody [syn: company, companion,
       accompany, keep company]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "accompany":
   agree, associate, associate with, assort with, attend,
   band together, be in phase, be in time, chaperon, chaperone, chord,
   coexist, coextend, coincide, combine, companion, concertize,
   concur, confederate, consociate, consort with, contemporize,
   convoy, couple with, do, escort, execute, flock together,
   go along with, go with, hang around with, herd together, interpret,
   isochronize, keep company with, keep in step, keep pace with,
   make music, match, perform, play, play by ear, render, run with,
   squire, symphonize, synchronize, time, usher, wait on