- Geometry. a solid contained by four plane faces; a triangular pyramid.
- any of various objects resembling a tetrahedron in the distribution of its faces or apexes.
Origin of tetrahedron
Examples from the Web for tetrahedra
The atoms are arranged in two tetrahedra with a common apex, and the relationship is maintained in the meta-body, a septet.
The globe, e, is a new form, the four tetrahedra of the proto level making a single twelve-atomed one on the meta.
The smallest particles of fire are tetrahedra, of air octahedra, of water icosahedra.A Critical History of Greek Philosophy
W. T. Stace
- a solid figure having four plane faces. A regular tetrahedron has faces that are equilateral trianglesSee also polyhedron
- any object shaped like a tetrahedron
Word Origin and History for tetrahedra
solid figure contained by four triangular surfaces, 1560s, from Late Greek tetraedron, originally neuter of tetraedros (adj.) "four-sided," from tetra- "four" + hedra "seat, base, chair, face of a geometric solid," from PIE root *sed- (1) "to sit" (see sedentary).
- A polyhedron having four faces.