- a cold-blooded vertebrate animal of a class that comprises the frogs, toads, newts, salamanders, and caecilians. They are distinguished by having an aquatic gill-breathing larval stage followed (typically) by a terrestrial lung-breathing adult stage.
- Class Amphibia: orders Urodela (newts and salamanders), Anura (frogs and toads), and Gymnophiona (caecilians)
mid 17th century (in the sense 'having two modes of existence or of doubtful nature'): from modern Latin amphibium 'an amphibian', from Greek amphibion (noun use of amphibios 'living both in water and on land', from amphi 'both' + bios 'life')
The beginning of amphibian should be spelled amphi-; it comes from the Greek word amphi-, meaning 'both'.