amphibian

American  

[am-fib-ee-uhn] / æmˈfɪb i ən /

noun

• amphibians
  plural

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

Derived Forms

• nonamphibian
  adjective

Inflected Forms

Nouns

• amphibians
  plural

Etymology

Origin of amphibian

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

Explanation

An amphibian is a cold-blooded vertebrate animal that is born in water and breathes with gills. As the larva grows into its adult form, the animal's lungs develop the ability to breathe air, and the animal can live on land. Frogs, toads, and salamanders are all amphibians. The word amphibian comes from the Greek word amphibios, which means "to live a double life." The noun amphibian has its roots in the words amphi, meaning "of both kinds," and bios, meaning "life." The word is used for the class of animals that spend part of their lives in water and part on land. The word can also be used as an adjective to describe the animals that live this way. You might be interested to know that the largest amphibian weighs about 140 pounds and the smallest weighs only a few grams.

Example Sentences

See Examples For:

amphibian amphibians

"Many teeth from Saurichthys were once mistaken for those of an amphibian, and that misunderstanding continued well into the 20th Century," said Museum Wales curator Cindy Howells.

From BBC ● Sep. 28, 2026

The extinct spadefoot toad, now named Spea labreae, represents the first new extinct amphibian species discovered from the famous fossil site.

From Science Daily ● Aug. 16, 2026

Also detailed in the Journal of Vertebrate Paleontology is the first record of another amphibian: the Mexican burrowing toad —Rhinophrynus.

From Los Angeles Times ● Aug. 7, 2026

A nature-loving 10-year-old girl who found an endangered amphibian under a bridge has left her mum in "shock, surprise and disbelief".

From BBC ● Apr. 23, 2026

I make a drawing of the inside of the frog, with all its curlicues and bulbs, its tiny lungs, its cold-blooded amphibian heart.

From "Cat's Eye" by Margaret Atwood

Working with the Zoological Society of London, WWF tracks nearly 36,000 populations of almost 6,000 species of mammals, birds, fish, reptiles and amphibians.

From BBC ● Oct. 8, 2026

These were even thought to be from amphibians well into the 20th Century, rather than the fish that experts now know they were.

From BBC ● Sep. 28, 2026

That exceptional preservation has made Pedrera de Meià an important site for studying Lower Cretaceous fish, amphibians, reptiles, and plants.

From Science Daily ● Sep. 15, 2026

The same fragility may also mean that many extinct reptiles and amphibians have disappeared from the fossil record entirely.

From Science Daily ● Aug. 16, 2026

Lily looks up, awed by my knowledge of amphibians.

From "South of Somewhere" by Kalena Miller

Related Words

• frog
• salamander
• toad