The antonyms for the word "unacceptability" are acceptability, suitability, adequacy, and appropriateness. These terms refer to the quality of being acceptable, suitable, adequate, or appropriate. Acceptability implies conformity to standards and fulfilling requirements. Suitability reflects compatibility and appropriateness for a particular need, purpose, or situation. Adequacy denotes sufficiency, competency, or completeness. And, appropriateness signifies propriety or relevance to the circumstance. Therefore, when the opposite of "unacceptability" is applied, it implies that the subject is satisfactory, compliant, and suitable for its intended purpose, rather than defective, disapproved, or inappropriate.