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]

The Collaborative International Dictionary of English v.0.48:

En rapport \En` rap`port"\ [F.]
   In accord, harmony, or sympathy; having a mutual, esp. a
   private, understanding; of a hypnotic subject, being in such
   a mental state as to be especially subject to the influence
   of a particular person or persons.
   [Webster 1913 Suppl.]

Moby Thesaurus II by Grady Ward, 1.0:

117 Moby Thesaurus words for "en rapport":
   accordant, affable, affinitive, affirmative, agreeable, agreeing,
   akin, amiable, amicable, answerable, appertaining, associative,
   at one, attuned, blissful, cheerful, coexistent, coexisting,
   coherent, coincident, coinciding, commensurate, comparable,
   comparative, compatible, complaisant, concordant, concurring,
   conformable, congenial, congruent, congruous, connective,
   consentaneous, consentient, consistent, consonant, cooperating,
   cooperative, cordial, correlative, correspondent, corresponding,
   desirable, dulcet, empathetic, empathic, enjoyable, equivalent,
   fair, fair and pleasant, felicific, felicitous, fine, frictionless,
   genial, good, goodly, gracious, grateful, gratifying, harmonious,
   heart-warming, honeyed, in accord, in agreement, in concert,
   in rapport, in sync, in synchronization, in tune, inaccordance,
   inharmony, likable, like-minded, linking, mellifluous, mellow,
   nice, of a piece, of like mind, of one mind, on all fours,
   peaceful, pertaining, pertinent, pleasant, pleasing, pleasurable,
   pleasure-giving, pleasureful, positive, proportionable,
   proportional, proportionate, reconcilable, referable, referring,
   relating, relational, relative, rewarding, satisfying,
   self-consistent, sweet, symbiotic, sympathetic, synchronized,
   synchronous, together, unanimous, understanding, uniform,
   unisonant, unisonous, united, welcome