The term 'Aquatic Lung' refers to a type of breathing organ found in some aquatic animals, such as fish and amphibians. It is also known as a GILL, which is a four-letter word. Gills are organs that allow aquatic animals to extract oxygen from the water they live in. They are composed of thin filaments that absorb oxygen from the water and then transport it to the animal's bloodstream. Gills are essential for aquatic animals to survive in their environment.