Being consonant means being in agreement or harmony. The antonyms for this word are disharmony, discord, disagreement, inconsistency, incongruity, and incompatibility. Disharmony implies a lack of harmony or agreement, while discord refers to a lack of agreement or unity in sound or tone. Inconsistency suggests a lack of coherence or stability, while incongruity refers to a lack of harmony or agreement in form, quality, or character. Finally, incompatibility implies a lack of compatibility or suitability between different people, things, or ideas. These antonyms are useful in describing situations where there is a lack of agreement, harmony or similarity.