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

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Etymology

Origin of amphibian

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

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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

In a rescue mission on Wednesday, amphibian and reptile experts found dead wildlife, but also some survivors which were collected and relocated.

From BBC ● Aug. 21, 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

Tillack has worked closely with colleagues in Nepal for 35 years on research projects involving Himalayan reptile and amphibian biodiversity.

From Science Daily ● May 26, 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

Maria was the first to document the life stages of this unusual amphibian, which attaches its eggs to its back.

From "The Girl Who Drew Butterflies: How Maria Merian's Art Changed Science" by Joyce Sidman

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

Backshall studied at Canterbury Christ Church, carrying out research into venoms from amphibians, and later received an honorary doctorate from the university.

From BBC ● Oct. 2, 2026

The fossil record includes spiders, flies, wasps or beetles, insect larvae, crustaceans, vertebrates such as fish and amphibians, and a remarkable diversity of plants.

From Science Daily ● Sep. 15, 2026

The Assn. of Zoos and Aquariums Wildlife Confiscations Network was notified about a box truck filled with more than 2,000 animals, including fish, reptiles, invertebrates and amphibians, according to the release.

From Los Angeles Times ● Aug. 28, 2026

Lily looks up, awed by my knowledge of amphibians.

From "South of Somewhere" by Kalena Miller

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Related Words

• frog
• salamander
• toad

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