WordNet sense 1 (of words so related that one contrasts with the other):

contrastive

WordNet sense 2 (of words: having opposite meanings):

antonymous

WordNet sense 3 (not easy to combine harmoniously):

unsuited, ill-sorted, mismated

WordNet sense 4 (either not matched or unsuitably matched):

mismatched

WordNet sense 5 (not compatible with other facts):

discrepant

WordNet sense 6 (displaying a lack of consistency):

inconsistent

WordNet sense 7 (not in keeping with what is correct or proper):

inappropriate, unfitting

WordNet sense 8 (lacking in harmony or compatibility or appropriateness):

incongruous

WordNet sense 9 (not agreeing with your tastes or expectations):

unsympathetic

WordNet sense 10 ((chemistry, physics) incapable of mixing):

immiscible, unmixable, non-miscible

WordNet sense 11 (used of plant stock or scions; incapable of being grafted):

uncongenial

WordNet sense 12 (unable to be both true at the same time):

contradictory

WordNet sense 13 (incapable of harmonious association):

antagonistic