noun

1. any of a class (Amphibia) of coldblooded, scaleless vertebrates, consisting of frogs, toads, newts, salamanders, and caecilians, that usually begin life in the water as tadpoles with gills and later develop lungs
2. any amphibious animal or plant
3. any aircraft that can take off from and come down on either land or water
4. a tank or other vehicle that can travel on either land or water

Etymology: < ModL Amphibia < Gr amphibia, neut. pl. of amphibios: see amphibious

adjective

1. of amphibians
2. amphibious