The Collaborative International Dictionary of English v.0.48:

Concordance \Con*cord"ance\, n. [F., fr. LL. concordantia.]
   1. Agreement; accordance.
      [1913 Webster]

            Contrasts, and yet concordances.      --Carlyle.
      [1913 Webster]

   2. (Gram.) Concord; agreement. [Obs.] --Aschlam.
      [1913 Webster]

   3. An alphabetical verbal index showing the places in the
      text of a book where each principal word may be found,
      with its immediate context in each place.
      [1913 Webster]

            His knowledge of the Bible was such, that he might
            have been called a living concordance. --Macaulay.
      [1913 Webster]

   4. A topical index or orderly analysis of the contents of a
      book.
      [1913 Webster]

WordNet (r) 3.0 (2006):

concordance
    n 1: a harmonious state of things in general and of their
         properties (as of colors and sounds); congruity of parts
         with one another and with the whole [syn: harmony,
         concord, concordance]
    2: agreement of opinions [syn: harmony, concord,
       concordance]
    3: an index of all main words in a book along with their
       immediate contexts

Moby Thesaurus II by Grady Ward, 1.0:

205 Moby Thesaurus words for "concordance":
   acclamation, accompaniment, accord, accordance, affinity, agape,
   agreement, agreement of all, alliance, amity, assent, association,
   atlas, attune, attunement, bipartisanship, bonds of harmony,
   brotherly love, cahoots, calendar, caritas, casebook, catalog,
   catalogue raisonne, cement of friendship, charity, chime, chiming,
   chorus, city directory, classified catalog, co-working, coaction,
   coadjuvancy, coadministration, coagency, cochairmanship,
   codirectorship, coherence, coincidence, collaboration,
   collaborativeness, collectivism, collectivity, collusion,
   combination, combined effort, commensalism, common assent,
   common consent, common effort, common enterprise, communalism,
   communion, communism, communitarianism, community,
   community of interests, compatibility, complicity, concentus,
   concert, concerted action, concomitance, concord, concourse,
   concurrence, confluence, conformance, conformation, conformity,
   congeniality, congruence, congruency, congruity, conjunction,
   consensus, consensus gentium, consensus of opinion,
   consensus omnium, consent, consentaneity, consilience, consistency,
   consonance, consonancy, consort, conspiracy, cooperation,
   cooperativeness, correspondence, cyclopedia, diapason, diatesseron,
   dictionary catalog, directory, duet, duumvirate, ecumenicalism,
   ecumenicism, ecumenism, empathy, encyclopedia, equivalence, esprit,
   esprit de corps, euphony, feeling of identity, fellow feeling,
   fellowship, frictionlessness, gazetteer, general acclamation,
   general agreement, general consent, general voice, good vibes,
   good vibrations, happy family, harmonics, harmony, heavy harmony,
   homophony, identity, index, intersection, joining of forces,
   joint effort, joint operation, junction, kinship, like-mindedness,
   love, mass action, meeting of minds, monochord, monody, morale,
   mutual assistance, mutual understanding, mutualism, mutuality,
   octet, one accord, one voice, oneness, overlap, parallelism,
   parasitism, peace, phone book, polyglot, pooling,
   pooling of resources, pulling together, quartet, quintet, rapport,
   rapprochement, reciprocity, record book, reference book, same mind,
   saprophytism, self-consistency, septet, sextet, sharing,
   simultaneity, single voice, solidarity, source book, studbook,
   symbiosis, symmetry, sympathy, symphony, sync, synchronism,
   synchronization, synergism, synergy, tally, team spirit, teamwork,
   telephone book, telephone directory, three-part harmony, timing,
   total agreement, trio, triumvirate, troika, tune, unanimity,
   unanimousness, understanding, uniformity, union, unison,
   unisonance, united action, unity, universal agreement,
   work of reference