There are several synonyms for the term "aquatic fern," which refers to a type of fern plant that typically grows in or near bodies of water. One such synonym is "water fern," which highlights the plant's habitat in aquatic environments. Another synonym is "submerged fern," which emphasizes the fact that the fern is often fully submerged in water. "Marsh fern" is another synonym that points to the plant's ability to grow in wetland areas. Finally, "littoral fern" is a synonym that refers to the plant's tendency to grow in the shallow regions near the edge of a body of water.