- any vertebrate having four limbs or, as in the snake and whale, having had four-limbed ancestors.
- an object, as a caltrop, having four projections radiating from one central node, with each forming an angle of 120° with any other, so that no matter how the object is placed on a relatively flat surface, three of the projections will form a supporting tripod and the fourth will point directly upward.
- having four limbs or descended from four-limbed ancestors.
Origin of tetrapod
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for tetrapod
Contributions to the question of the origin of the tetrapod limb.The Ancestry of Modern Amphibia: A Review of the Evidence
Theodore H. Eaton
Tetrapod, tet′ra-pod, n. an insect distinguished by having but four perfect legs.
- any vertebrate that has four limbs
- Also called: caltrop a device consisting of four arms radiating from a central point, each at about 109° to the others, so that regardless of its position on a surface, three arms form a supporting tripod and the fourth is vertical
- engineering a very large cast concrete structure of a similar shape piled in large numbers round breakwaters and sea defence systems to dissipate the energy of the waves
Word Origin and History for tetrapod
Online Etymology Dictionary, © 2010 Douglas Harper
- Having four feet, legs, or leglike appendages.
- Any of various mostly terrestrial vertebrates that breathe air with lungs. Most tetrapods have two pairs of limbs, though some, such as whales and snakes, have lost one or both pairs. Tetrapods include the amphibians, reptiles, birds, mammals, and various extinct groups, and evolved from lobe-finned fish during the late Devonian Period. Tetrapods are classified according to the structure of their skull into anapsids, diapsids, and synapsids.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.