The word "moss-grown" refers to something that is covered in or overgrown with moss. Its antonyms would be words that describe something that is not covered in moss. Possible antonyms for "moss-grown" could include words such as clean, sleek, smooth, new, modern, polished, pristine, unblemished, unspoiled, and fresh. These words evoke images of surfaces that are free of moss or any kind of growth, and that appear to be well-maintained or recently created. Using antonyms can help writers create a strong contrast between different scenarios or objects, making their writing more vivid and engaging.