What does tetrahedron mean?
A tetrahedron is a three-dimensional solid made from four triangular faces, joined along six edges and meeting at four vertices. The most familiar version is the regular tetrahedron, in which every face is an equilateral triangle and all edges have the same length. Its balanced proportions and rotational symmetries make it important in geometry and among the five Platonic solids. The word also appears in scientific and technical contexts, including molecular structures, where atoms can be arranged in a tetrahedral form, and in computer graphics, where collections of tetrahedra form meshes representing three-dimensional surfaces and volumes. Because it describes a specific and recognizable solid, “tetrahedron” is more precise than the general term “pyramid.” The plural is usually “tetrahedra,” although “tetrahedrons” is also accepted, especially outside specialist mathematical writing.
nounA polyhedron with four triangular faces, six edges, and four vertices. In its regular form, all four faces are equilateral triangles.
- A polyhedron composed of four triangular faces, with four vertices and six edges; when regular, its faces are equilateral triangles.
"The model is based on a regular tetrahedron, whose four identical triangular faces meet at four vertices."
"The sculpture was made from a regular tetrahedron mounted on a slender pedestal."
"In computational geometry, a tetrahedron mesh approximates the shape of a complex object."
“Tetrahedra” is the standard mathematical plural. “Tetrahedrons” is also accepted in general usage.
"Four interlocking tetrahedra form the basis of the model."
A regular tetrahedron has only four faces, yet it is one of the five Platonic solids, admired for a symmetry that looks almost impossibly perfect.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does tetrahedron come from?
“Tetrahedron” combines the Greek prefix tetra-, meaning “four,” with the geometric term -hedron, from Greek hēdron, meaning “seat” or “base” and referring to a face of a solid. The name reflects the traditional Greek and Latin practice of naming polyhedra according to the number of their faces. Related English words such as “tetrad” and “tetravalent” reflect the same Greek numerical root.
Related word forms
How tetrahedron is actually used
A formal mathematical and scientific term, used especially in geometry, chemistry, engineering, and computer graphics. It is uncommon in everyday speech.
Easily confused with tetrahedron
A tetrahedron is a noun naming a four-faced solid, while tetrahedral is an adjective describing something shaped like or based on such a solid.