amphibian

American  

[am-fib-ee-uhn] / æmˈfɪb i ən /

noun

1. any cold-blooded vertebrate of the class Amphibia, comprising frogs and toads, newts and salamanders, and caecilians, the larvae being typically aquatic, breathing by gills, and the adults being typically semiterrestrial, breathing by lungs and through the moist, glandular skin.

2. an amphibious plant.

3. an airplane designed for taking off from and landing on both land and water.

4. Also called amtrac.  a flat-bottomed, armed, military vehicle, equipped with both tracks and a rudder, that can travel either on land or in water, used chiefly for landing assault troops.

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adjective

1. belonging or pertaining to the Amphibia.

2. amphibious.

amphibian British  

/ æmˈfɪbɪən /

noun

1. any cold-blooded vertebrate of the class Amphibia, typically living on land but breeding in water. Their aquatic larvae (tadpoles) undergo metamorphosis into the adult form. The class includes the newts and salamanders, frogs and toads, and caecilians

2. a type of aircraft able to land and take off from both water and land

3. any vehicle able to travel on both water and land

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adjective

1. another word for amphibious

2. of, relating to, or belonging to the class Amphibia

amphibian Scientific  

/ ăm-fĭb′ē-ən /

1. A cold-blooded, smooth-skinned vertebrate of the class Amphibia. Amphibians hatch as aquatic larvae with gills and, in most species, then undergo metamorphosis into four-legged terrestrial adults with lungs for breathing air. The eggs of amphibians are fertilized externally and lack an amnion. Amphibians evolved from lobe-finned fish during the late Devonian Period and include frogs, toads, newts, salamanders, and caecilians.

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Word History

Amphibians, not quite fish and not quite reptiles, were the first vertebrates to live on land. These cold-blooded animals spend their larval stage in water, breathing through their gills. In adulthood they usually live on land, using their lungs to breath air. This double life is also at the root of their name, amphibian, which, like many scientific words, derives from Greek. The Greek prefix amphi– means “both,” or “double,” and the Greek word bios means “life.” Both these elements are widely used in English scientific terminology: bios, for example, is seen in such words as biology, antibiotic, and symbiotic.

Other Word Forms

• nonamphibian adjective

Etymology

Origin of amphibian

1630–40; < Latin amphibi ( a ), neuter plural of amphibius (adj.) ( amphibious ) + -an

Example Sentences

These include stricter import regulations, routine pathogen screening, quarantine measures, and coordinated global monitoring to better protect native amphibian species from future outbreaks.

From Science Daily • Jan. 19, 2026

Their projections suggest there could be as many as 115,000 fish species and 41,000 amphibian species, compared with about 42,000 fish and 9,000 amphibians currently described.

From Science Daily • Dec. 24, 2025

But the relative lack of rain this spring and summer could lead to lower insect and amphibian numbers next year since eggs may not be laid and wetland areas are drying up.

From BBC • Jul. 25, 2025

“I haven’t seen this level of positivity and excitement ever,” said Stephanie Carpenter, a reptile and amphibian keeper.

From Los Angeles Times • Jul. 18, 2025

My heart, that amphibian, moving that moment between two elements: one, excitement; the other, fear.

From "Middlesex: A Novel" by Jeffrey Eugenides

Related Words

• frog
• salamander
• toad