Number & MeasureGreek → English
Tetrahedron
/ˌtɛtrəˈhiːdrən/noun
A solid with four triangular faces, the simplest of the Platonic solids.
The Greek roots
τέτρα-
tétra-
four
ἕδρα
hédra
seat, face
Literally: “four-seated”
The story of the word
Plato handed this solid to fire in the Timaeus, reasoning that the shape with the sharpest points ought to be the element that pricks and burns. Euclid's final book constructs all five regular solids and ends by proving there can be no sixth. Chemists later borrowed the word for the arrangement carbon holds its four bonds in, which is why organic molecules are drawn as they are.
- How it travelled
- Ancient Greek → Latin → English
- First recorded
- 1560s
The same roots elsewhere
Other languages reached for exactly the same Greek pieces.
Same family
hexahedronoctahedrontetrapodpolyhedron
In a sentence
Four equal triangles fold into a tetrahedron with no tab left over.