[ am'fɪbɪən ]
■ noun Zoology a cold-blooded vertebrate animal of a class (Amphibia) that comprises the frogs, toads, newts, salamanders, and caecilians, distinguished by an aquatic gill-breathing larval stage followed by a terrestrial lung-breathing adult stage.
Origin
C17 (in the sense 'of dual or doubtful nature'): from mod. L. amphibium 'an ~', from Gk amphibion (noun use of amphibios 'living both in water and on land', from amphi 'both' + bios 'life').