The Collaborative International Dictionary of English v.0.48:

Attune \At*tune"\, v. t. [imp. & p. p. Attuned; p. pr. & vb.
   n. Attuning.] [Pref. ad- + tune.]
   [1913 Webster]
   1. To tune or put in tune; to make melodious; to adjust, as
      one sound or musical instrument to another; as, to attune
      the voice to a harp.
      [1913 Webster]

   2. To arrange fitly; to make accordant.
      [1913 Webster]

            Wake to energy each social aim,
            Attuned spontaneous to the will of Jove. --Beattie.
      [1913 Webster]

WordNet (r) 3.0 (2006):

attune
    v 1: adjust or accustom to; bring into harmony with