The Collaborative International Dictionary of English v.0.48:

Concordant \Con*cord"ant\, a. [L. concordans, p. pr. of
   concordare: cf. F. concordant. See Concord.]
   Agreeing; correspondent; harmonious; consonant.
   [1913 Webster]

         Were every one employed in points concordant to their
         natures, professions, and arts, commonwealths would
         rise up of themselves.                   --Sir T.
                                                  Browne
   [1913 Webster]

WordNet (r) 3.0 (2006):

concordant
    adj 1: in keeping; "salaries agreeable with current trends";
           "plans conformable with your wishes"; "expressed views
           concordant with his background" [syn: accordant,
           agreeable, conformable, consonant, concordant]
    2: being of the same opinion [syn: concordant,
       concurring(a)]

Moby Thesaurus II by Grady Ward, 1.0:

177 Moby Thesaurus words for "concordant":
   accompanying, accordant, according, affirmative, agreeable,
   agreeing, akin, amicable, anal, answerable, associate, associated,
   assonant, assonantal, at one, at one with, at peace, attuned,
   blended, blending, bloodless, bourgeois, calm,
   carried by acclamation, chiming, coacting, coactive, coadjutant,
   coadjuvant, coadunate, coefficient, coexistent, coexisting,
   coherent, coincident, coinciding, collaborative, collective,
   collectivist, collectivistic, collusive, combined, combining,
   commensal, commensurate, common, communal, communalist,
   communalistic, communist, communistic, communitarian, compatible,
   compulsive, concerted, concomitant, concurrent, concurring,
   conformable, conformist, congenial, congruent, congruous, conjoint,
   conniving, consentaneous, consentient, consilient, consistent,
   consonant, conspiratorial, conventional, cooperant, cooperating,
   cooperative, coordinate, correspondent, corresponding, coworking,
   ecumenic, empathetic, empathic, en rapport, equivalent, fellow,
   formalistic, frictionless, halcyon, harmonic, harmonious,
   harmonized, harmonizing, homophonic, idyllic, in accord,
   in agreement, in chorus, in concert, in concord, in keeping,
   in line, in rapport, in step, in sync, in synchronization, in tune,
   in unison, inaccordance, inharmony, joint, kosher, like-minded,
   meeting, monodic, monophonic, mutual, noncompetitive, of a piece,
   of like mind, of one accord, of one mind, on all fours, orderly,
   orthodox, pacific, parasitic, pastoral, peaceable, peaceful,
   peacetime, pedantic, piping, plastic, positive, precisianistic,
   proportionate, quiet, reciprocal, reconcilable, restful,
   saprophytic, self-consistent, serene, soft, solid, square,
   straight, stuffy, symbiotic, sympathetic, symphonious,
   synchronized, synchronous, synergetic, synergic, synergistic,
   together, traditionalist, tranquil, tuned, unanimous, unchallenged,
   uncompetitive, uncontested, uncontradicted, uncontroverted,
   understanding, uniform, unisonant, unisonous, united, uniting,
   unopposed, untroubled, uptight, with one consent, with one voice