Antonyms of "make worse" could include "improve," "enhance," "amplify," "boost," and "uplift." To improve something means to make it better or enhance its quality, the opposite of making it worse. Enhance means to add value or improve quality or properties. Amplify means to increase the size, volume, strength or effect. To boost something is to increase or raise its level, and to uplift something is to elevate it, make it better or better off. All these words imply a positive impact on something or the opposite of making it worse.