The term "most reformatory" suggests something that has a strong inclination or ability to reform someone. The antonyms for "most reformatory" would therefore refer to things or people that hinder progress, discourage positive change, or are not focused on reform. Some examples of antonyms would include: regressive, obstructive, reactionary, unprogressive, retrograde, stagnant, unchanging, unyielding, stubborn, and unresponsive. These words imply a lack of openness to new ideas or approaches, and an unwillingness to adapt to changing circumstances. Overall, the antonyms for "most reformatory" imply a resistance to change and a preference for the status quo.