WordNet (r) 3.0 (2006):

repudiative
    adj 1: rejecting emphatically; e.g. refusing to pay or
           disowning; "a veto is a repudiative act"

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "repudiative":
   abjuratory, abnegative, adversative, breakaway, contradicting,
   contradictory, contrary, creedless, denying, disaffirming,
   disallowing, disavowing, disbelieving, disclaiming, disowning,
   faithless, heretical, incredulous, irreligious, minimifidian,
   mugwumpian, mugwumpish, negative, negatory, nonbelieving,
   nullifidian, opposing, recanting, renunciative, renunciatory,
   repudiatory, repugnant, revocative, revocatory, schismatic,
   secessionist, separatist, unbelieving, unconfident, unconverted,
   unconvinced, without faith