adj. & n.
adj. 1 living both on land and in water. 2 Zool. of or relating to the class Amphibia. 3 (of a vehicle) able to operate on land and water.
n. 1 Zool. any vertebrate of the class Amphibia, with a life history of an aquatic gill-breathing larval stage followed by a terrestrial lung-breathing adult stage, including frogs, toads, newts, and salamanders. 2 (in general use) a creature living both on land and in water. 3 an amphibian vehicle.