Well-grown is an adjective that is often used to describe something that has grown or developed steadily and healthily. There are many synonyms for the word well-grown, including fully-grown, matured, developed, flourishing, thriving, and thrivingly. These words all refer to the fact that something has grown or progressed in a positive way. Other synonyms for well-grown include sturdy, robust, healthy, and thriving. These words can be used to describe plants, animals, people, or anything that has grown or developed in a positive way. Ultimately, the synonym you choose will depend on the context in which you are using it and the particular qualities that you want to emphasize.