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

Scientists have uncovered why some amphibian populations rebound after being devastated by a deadly fungal disease that has wiped out frogs and toads around the world.

From Science Daily ● Jul. 15, 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

A 2023 analysis of roughly 8,000 amphibian species found that two out of five are threatened with extinction, making amphibians the most endangered group of vertebrates.

From Science Daily ● Mar. 9, 2026

I met a married couple at a No Kings rally in Sacramento who were dressed up as dinosaurs, inspired by the Portland Frog, an activist who wears an inflatable amphibian suit.

From Los Angeles Times ● Dec. 28, 2025

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

From "Middlesex: A Novel" by Jeffrey Eugenides

Young amphibians are largely protected because tadpoles and larvae lack the keratin rich skin that Bd feeds on.

From Science Daily ● Jul. 15, 2026

Both he and Pardo also noted that the study underscores that amphibians are impressive evolutionary creatures in their own right.

From Barron's ● Jun. 18, 2026

Salty water could be preventing the recovery of one of the UK's rarest amphibians by making former breeding sites unsuitable for their survival, a study has concluded.

From BBC ● May 31, 2026

Tanyka belongs to a broad group of vertebrates known as tetrapods, which includes all four-limbed animals with backbones such as reptiles, birds, mammals, and amphibians.

From Science Daily ● May 1, 2026

Congress because it killed millions of birds, fish, and amphibians after World War II, the insecticide called DDT was still being used in South America.

From "Frightful's Mountain" by Jean Craighead George

Related Words

• frog
• salamander
• toad