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tetrahedron

[te-truh-hee-druh n]
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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.

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 tetrahedra

Historical Examples of tetrahedra

  • The globe, e, is a new form, the four tetrahedra of the proto level making a single twelve-atomed one on the meta.

    Occult Chemistry

    Annie Besant and Charles W. Leadbeater

  • The atoms are arranged in two tetrahedra with a common apex, and the relationship is maintained in the meta-body, a septet.

    Occult Chemistry

    Annie Besant and Charles W. Leadbeater

  • The smallest particles of fire are tetrahedra, of air octahedra, of water icosahedra.

British Dictionary definitions for tetrahedra

tetrahedron

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 tetrahedra

tetrahedron

n.

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).

Online Etymology Dictionary, © 2010 Douglas Harper
tetrahedra in Science

tetrahedron

[tĕt′rə-hē′drən]

Plural tetrahedrons tetrahedra

A polyhedron having four faces.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.