The Collaborative International Dictionary of English v.0.48:

Inconsonant \In*con"so*nant\, a. [L. inconsonans. See In- not,
   and Consonant.]
   Not consonant or agreeing; inconsistent; discordant. --
   In*con"so*nant*ly, adv.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "inconsonant":
   abnormal, absurd, anomalous, assorted, at odds, at variance,
   contrary, contrasted, contrasting, departing, deviating, deviative,
   different, differentiated, differing, disaccordant, disagreeing,
   disconsonant, discordant, discrepant, discrete, discriminated,
   disjoined, disparate, disproportionate, dissimilar, dissonant,
   distinct, distinguished, divergent, diverging, divers, diverse,
   diversified, heterogeneous, ill-matched, ill-suited,
   in disagreement, inaccordant, incoherent, incommensurable,
   incommensurate, incompatible, incongruent, incongruous,
   inconsequent, inconsistent, inharmonious, irreconcilable, many,
   mismated, motley, multifarious, out of proportion, oxymoronic,
   paradoxical, poles apart, poles asunder, self-contradictory,
   separate, separated, several, unconformable, uncongenial, unequal,
   unlike, variant, varied, variegated, various, varying,
   widely apart, worlds apart