The Collaborative International Dictionary of English v.0.48:

Rapport \Rap*port"\ (r[a^]p*p[=o]rt"; F. r[.a]`p[^o]r"), n. [F.,
   fr. rapporter to bring again or back, to refer; pref. re- re-
   + apporter to bring, L. apportare. Cf. Report.]
   Relation; proportion; conformity; correspondence; accord.
   [1913 Webster]

         'T is obvious what rapport there is between the
         conceptions and languages in every country. --Sir W.
                                                  Temple.
   [1913 Webster]

   En` rap`port" ([aum]N` r[.a]`p[^o]r") [F.], in accord,
      harmony, or sympathy; having a mutual, especially a
      private, understanding; in hypnotism, in that relation of
      sympathy which permits influence or communication.
      [1913 Webster]

WordNet (r) 3.0 (2006):

rapport
    n 1: a relationship of mutual understanding or trust and
         agreement between people [syn: rapport, resonance]

Moby Thesaurus II by Grady Ward, 1.0:

156 Moby Thesaurus words for "rapport":
   accord, accordance, addition, adjunct, affability, affairs,
   affiliation, affinity, agape, agreeability, agreeableness,
   agreement, alliance, amenity, amiability, amicability, amity,
   an in, approximation, assemblage, assent, association, bliss,
   blissfulness, bond, bonds of harmony, brotherly love, camaraderie,
   caritas, cement of friendship, charity, chorus, closeness,
   coherence, coincidence, combination, communion, community,
   community of interests, compatibility, complaisance, concert,
   concord, concordance, conformance, conformation, conformity,
   congeniality, congruence, congruency, congruity, connectedness,
   connection, consistency, consonance, consort, contiguity,
   contrariety, cooperation, cordiality, correspondence, dealings,
   deduction, disjunction, empathy, enjoyableness, equivalence,
   esprit, esprit de corps, favor, favorable regard,
   feeling of identity, felicitousness, fellow feeling, fellowship,
   filiation, frictionlessness, friendly relations, geniality,
   good graces, good terms, good understanding, good vibes,
   good vibrations, goodliness, goodness, goodwill, graciousness,
   happy family, harmoniousness, harmony, homology, identity,
   intercourse, intersection, intimacy, junction, kinship, liaison,
   like-mindedness, link, linkage, linking, love, mellifluousness,
   mellowness, mutual attraction, mutual regard, mutual understanding,
   mutuality, nearness, niceness, oneness, overlap, parallelism,
   peace, pleasance, pleasantness, pleasantry, pleasingness,
   pleasurability, pleasurableness, pleasure, pleasurefulness,
   propinquity, proximity, rapprochement, reciprocity, regard,
   relatedness, relation, relations, relationship, respect,
   self-consistency, sharing, similarity, solidarity, sweetness,
   symmetry, sympathy, symphony, sync, synchronism, tally,
   team spirit, tie, tie-in, timing, understanding, uniformity, union,
   unison, unisonance, unity, welcomeness