tetrahedron

play
noun tet·ra·he·dron \ˌte-trə-ˈhē-drən\

Definition of tetrahedron

plural

tetrahedrons

or

tetrahedra

play \-drə\
  1. :  a polyhedron that has four faces

Did You Know?

The simplest tetrahedron is made of four equal-sided triangles: one is used as the base, and the other three are fitted to it and each other to make a pyramid. But the great pyramids of Egypt aren't tetrahedrons: they instead have a square base and four triangular faces, and thus are five-sided rather than four-sided.

Illustration of tetrahedron

Origin and Etymology of tetrahedron

New Latin, from Late Greek tetraedron, neuter of tetraedros having four faces, from Greek tetra- + hedra seat, face — more at sit


First Known Use: 1570


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