"Macroalga" is a scientific term commonly used to refer to large, multicellular algae found in marine environments. However, there are several synonyms to this term that can be employed to describe these seaweeds. One such synonym is "seaweed", a more general term encompassing a wide range of macroscopic marine algae. Another synonym is "kelp", which specifically refers to large brown seaweeds characterized by their elongated and leaf-like structures. Additionally, the term "giant algae" can be utilized to emphasize the exceptional size of these seaweeds. Consequently, whether referred to as seaweed, kelp, or giant algae, these synonyms all convey the concept of large, multicellular marine plants that play vital roles in aquatic ecosystems.