The word "lookdown" is a noun that refers to a specific type of fish. It is similar to a moonfish, but it has eyes that are positioned high on its flat, short forehead.
In more advanced discussions, you might find "lookdown" used in scientific contexts or when discussing ocean ecosystems. For example, "Researchers have noted that the lookdown plays a crucial role in the food chain of coastal waters."
In summary, "lookdown" is a specific noun used in marine biology to describe a type of fish that resembles a moonfish but has unique physical characteristics.