tetrahedron

[ te-truh-hee-druh n ]

/ ˌtɛ trəˈhi drən /

noun, plural tet·ra·he·drons, tet·ra·he·dra [te-truh-hee-druh] /ˌtɛ trəˈhi drə/.

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.

Nearby words

Origin of tetrahedron

1560–70; tetra- + -hedron, modeled on Late Greek tetráedron, noun use of neuter of tetráedros four-sided

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for tetrahedron

The tetrahedron in Fig. 32 may appear either as erect on its base or as leaning backward with its base seen from underneath.
Visual Illusions|Matthew Luckiesh
Round Mars describe a tetrahedron; the circle including this will be Jupiter.
The Martyrs of Science, or, The lives of Galileo, Tycho Brahe, and Kepler|David Brewster
From the sides of the hollow square sprang long arms of spheres, each tipped by a tetrahedron.
The Metal Monster|A. Merritt
About Mars' orbit describe a tetrahedron: the sphere containing this will be Jupiter's orbit.
The Life of Galileo Galilei, with Illustrations of the Advancement of Experimental Philosophy|John Elliot Drinkwater Bethune

That for the tetrahedron has 12 for its order, for the cube (or octahedron) 24, and for the icosahedron (or dodecahedron) 60.
Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 6|Various

British Dictionary definitions for tetrahedron

tetrahedron

/ (ˌtɛtrəˈhiːdrən) /

noun plural -drons or -dra (-drə)

a solid figure having four plane faces. A regular tetrahedron has faces that are equilateral trianglesSee also polyhedron

any object shaped like a tetrahedron

Derived Formstetrahedral, adjectivetetrahedrally, adverb

Word Origin for tetrahedron

C16: from New Latin, from Late Greek tetraedron; see tetra-, -hedron

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for tetrahedron

tetrahedron

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).