Illustration of tetrahedron
tetrahedron
noun
tet·ra·he·dron
ˌte-trə-ˈhē-drən
plural tetrahedrons or tetrahedra
ˌte-trə-ˈhē-drə
: 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.
Cite this Entry
“Tetrahedron.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tetrahedron. Accessed 10 Jul. 2026.
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