Antonyms for the term "retrograde metamorphosis" could be "progressive transformation", "forward evolution", or "developmental advancement". Retrograde metamorphosis refers to the process of devolving or regressing into an earlier, simpler stage of development, so it's opposite would be advancing forward into a more complex, mature state. A synonym for retrograde metamorphosis is "degeneration", so antonyms could also include "regeneration", "renewal", or "rejuvenation". These terms imply growth and improvement, whereas retrograde metamorphosis involves a decline and loss of complexity. Overall, antonyms for retrograde metamorphosis are words that suggest progress, growth, and positive change, rather than decay or regression.