The word "mossgrown" refers to something that is covered with moss. However, there are several other words that can be used to describe the same thing. Some synonyms for "mossgrown" include "mossy," "moss-covered," "moss-clad," "moss-draped," and "moss-laden." All of these words convey the same meaning and can be used in place of "mossgrown" in various contexts. For example, you can describe an old stone wall that is covered in moss as "mossy" or a tree that is draped in moss as "moss-draped." Using a variety of synonyms can help to add richness and variety to your writing and speech.