Most conscionable means the most ethical, responsible, and conscientious. Therefore, its antonyms would include unethical, irresponsible, and unconscientious. Other antonyms could include dishonest, corrupt, and unethical, as well as careless, thoughtless, and reckless. These words refer to individuals who are lacking in moral standards and do not take responsibility for their actions. The opposite of being the most conscionable is to be devoid of conscience or moral compass. Thus, it is essential to be cautious when using words that imply high ethical standards or morality and avoid polar opposites that may convey an entirely different meaning.