source: By Various; see each photo - this is a collage from four different works already in wikimedia commons:File:Litoria phyllochroa.JPGFile:Seymouria1.jpgFile:Notophthalmus viridescensPCCA20040816-3983A.jpgFile:Dermophis mexicanus.jpgAll of them are either under a free licence already in Wikicommons or in the public domain, CC BY-SA 3.0

a cold-blooded vertebrate animal of a class that comprises the frogs, toads, newts, and salamanders. They are distinguished by having an aquatic gill-breathing larval stage followed (typically) by a terrestrial lung-breathing adult stage.

〖通例～s〗 〘動〙 両生動物; (一般に)水陸両生の生物

a seaplane, tank, or other vehicle that can operate on land and on water.

水陸両用車［飛行機］

relating to amphibians:

〘動〙 両生類の, 水陸両生の

e.g. reptile and amphibian biology.

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’).