Most unaltered refers to something that has been left in its original state and has not been changed. The antonyms of this phrase could be any words that suggest modification or alteration in different degrees. Words such as "changed," "modified," "adjusted," "adapted," and "evolved" could be considered as antonyms to most unaltered. Other antonyms could include "transformed," "transfigured," "restructured," "updated," and "refined." These words suggest that something has been altered or transformed from its original state, indicating that it is not unaltered. Therefore, while "most unaltered" implies a sense of purity and authenticity, its antonyms suggest the opposite and present ideas of innovation and refashioning.