Any of several freshwater lobe-finned fishes of the group Dipnoi of Africa, South America, and Australia, having a lunglike organ that enables them to breathe air, especially during drought conditions.
Any of two orders (Ceratodiformes and Lepidosireniformes) of lobefins having lungs as well as gills.
Any of several tropical freshwater fish of the order or subclass Dipnoi that, in addition to having gills, have lunglike organs for breathing air. Lungfish have a long, narrow body, and certain species can survive periods of drought inside a mucus-lined cocoon in the mud. The lungfish and the coelacanths are the only living lobe-finned fishes.