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.
Examples of tetrahedron in a Sentence
Recent Examples on the Web
Constructed from Alexander Graham Bell’s simple tetrahedron cell, the Cygnet model consists of two equilateral paper triangles, connected and illuminated by a hidden light source.
—
Sofia Celeste, Footwear News, 10 Apr. 2025
Technically, a tetrahedron is a pyramid with all four faces of the shape being triangular, including the bottom of it, as is the design of the Tetra.
—New Atlas, 28 Sep. 2024
The would-be tetrahedron vessel is designed to be able to carry six Tom Cruise clone passengers, as well as three Victoria clones and one Julia crew members.
—New Atlas, 28 Sep. 2024
The resulting shape at the center of these overlapping spheres is known as the Reuleaux tetrahedron.
—Max Springer, Scientific American, 7 Aug. 2024
Three-dimensional objects can be similarly modeled; for these, the FEs are usually either blocks or tetrahedra, and the number of equations is typically much higher.
—Manil Suri, Scientific American, 25 June 2024
The stack of twisting, growing tetrahedra — a nod to nonlinear scientific advancement — looms, 42 feet high, like a sphinx.
—Megan Molteni, STAT, 14 Mar. 2023
Five years ago, at age 94, Fromson awarded a grant through his philanthropic foundation to the University of Connecticut to determine if a tetrahedron packed with different elements could improve the durability of the undersides of U.S. Humvees in Iraq.
—Kenneth R. Gosselin, courant.com, 28 June 2021
One group started chipping away at the foam volleyballs while another set about taping together basketballs into a tetrahedron.
—IEEE Spectrum, 16 Nov. 2020
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Sofia Celeste, Footwear News, 10 Apr. 2025
Technically, a tetrahedron is a pyramid with all four faces of the shape being triangular, including the bottom of it, as is the design of the Tetra.
—New Atlas, 28 Sep. 2024
The would-be tetrahedron vessel is designed to be able to carry six Tom Cruise clone passengers, as well as three Victoria clones and one Julia crew members.
—New Atlas, 28 Sep. 2024
The resulting shape at the center of these overlapping spheres is known as the Reuleaux tetrahedron.
—Max Springer, Scientific American, 7 Aug. 2024
Three-dimensional objects can be similarly modeled; for these, the FEs are usually either blocks or tetrahedra, and the number of equations is typically much higher.
—Manil Suri, Scientific American, 25 June 2024
The stack of twisting, growing tetrahedra — a nod to nonlinear scientific advancement — looms, 42 feet high, like a sphinx.
—Megan Molteni, STAT, 14 Mar. 2023
Five years ago, at age 94, Fromson awarded a grant through his philanthropic foundation to the University of Connecticut to determine if a tetrahedron packed with different elements could improve the durability of the undersides of U.S. Humvees in Iraq.
—Kenneth R. Gosselin, courant.com, 28 June 2021
One group started chipping away at the foam volleyballs while another set about taping together basketballs into a tetrahedron.
—IEEE Spectrum, 16 Nov. 2020
Cite this Entry
“Tetrahedron.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tetrahedron. Accessed 20 May. 2025.
Copy CitationKids Definition
tetrahedron
noun
tet·ra·he·dron
ˌte-trə-ˈhē-drən
plural tetrahedrons or tetrahedra
-drə
: a polyhedron that has four faces
tetrahedral
adjective
-drəl
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