1. Any of various cold-blooded, usually smooth-skinned vertebrates of the class Amphibia, characteristically hatching as an aquatic larva with gills and then transforming into an adult having air-breathing lungs. Frogs, toads, salamanders, and caecilians are amphibians.
2. An animal capable of living both on land and in water.
3. An aircraft that can take off and land on either land or water.
4. A tracked or wheeled vehicle that can operate both on land and in water.
[From New Latin Amphibia, class name, from Greek, neuter pl. of amphibios, amphibious : amphi-, amphi- + bios, life; see gwei- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.