A cold-blooded, smooth-skinned vertebrate of the class Amphibia, such as a frog or salamander, that characteristically hatches as an aquatic larva with gills. The larva then transforms into an adult having air-breathing lungs. An animal capable of living both on land and in water. An aircraft that can take off and land on either land or water. A tracked or wheeled vehicle that can operate both on land and in water.