amphibian [M17th] Amphibians live both in water and on land, and it is the idea of ‘living in both’ that gives us the word, which comes from Greek amphi ‘both’ (also found in amphitheatre [LME] from amphi ‘on both sides’ and theatron ‘place for beholding’) and bios ‘life’, source of words such as biology [L17th] and antibiotic [M19th]. Before it was applied specifically to frogs, toads, and newts, amphibian simply meant ‘having two modes of existence, of doubtful nature’.