There are numerous synonyms for the phrase "grow stronger". Some of these include "develop", "improve", "progress", "advance", "evolve" and "thrive". Other synonyms for the term include "mature", "blossom", "flourish", "prosper" and "surge". Depending on the context in which the phrase is used, some other synonyms that can be used include "escalate", "augment", "heighten", "enhance", "reinforce" and "amplify". All of these words connote the idea of something or someone becoming stronger, better or more powerful over time. They are useful when describing processes, people or institutions that undergo positive change and grow in strength over time.