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
3. 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
tetrapod in American English
(ˈtɛtrəˌpɑd)
noun
any vertebrate having four legs or limbs, including the mammals, birds, and reptiles