The Collaborative International Dictionary of English v.0.48:

Consonance \Con"so*nance\, Consonancy \Con"so*nan*cy\, n. [L.
   consonantia: cf. F. consonnance.]
   1. (Mus.) Accord or agreement of sounds produced
      simultaneously, as a note with its third, fifth, and
      eighth.
      [1913 Webster]

   2. Agreement or congruity; harmony; accord; consistency;
      suitableness.
      [1913 Webster]

            The perfect consonancy of our persecuted church to
            the doctrines of Scripture and antiquity. --Hammond.
      [1913 Webster]

            The optic nerve responds to the waves with which it
            is in consonance.                     --Tyndall.
      [1913 Webster]

   3. Friendship; concord. [Obs.]
      [1913 Webster]

            By the consonancy of our youth.       --Shak.

   Syn: Agreement; accord; consistency; unison; harmony;
        congruity; suitableness; agreeableness.
        [1913 Webster]

WordNet (r) 3.0 (2006):

consonance
    n 1: the repetition of consonants (or consonant patterns)
         especially at the ends of words [syn: consonance,
         consonant rhyme]
    2: the property of sounding harmonious [syn: consonance,
       harmoniousness]

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "consonance":
   accord, accordance, affinity, agreement, alliteration, assent,
   assonance, attune, attunement, blank verse, calm, chime, chiming,
   chorus, clink, coherence, coincidence, compatibility, concentus,
   concert, concord, concordance, conformance, conformation,
   conformity, congeniality, congruence, congruency, congruity,
   consistency, consonancy, consort, constancy, continuity,
   cooperation, correspondence, crambo, diapason, double rhyme,
   equability, equanimity, equilibrium, equivalence, euphony,
   evenness, eye rhyme, harmonics, harmony, heavy harmony,
   homogeneity, homophony, intersection, monochord, monody,
   monolithism, near rhyme, oneness, overlap, parallelism, peace,
   persistence, rapport, rhyme, rhyme royal, rhyme scheme,
   rhyming dictionary, self-consistency, single rhyme, slant rhyme,
   stability, steadfastness, steadiness, symmetry, symphony, sync,
   synchronism, synchronization, tail rhyme, tally,
   three-part harmony, timing, tune, uniformity, union, unison,
   unisonance, unity, unrhymed poetry, unruffledness