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[te-truh-hee-druh n] /ˌtɛ trəˈhi drən/
noun, plural tetrahedrons, tetrahedra
[te-truh-hee-druh] /ˌtɛ trəˈhi drə/ (Show IPA)
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 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for tetrahedron
Historical Examples
  • A scalene triangle abc might also be employed, or a tetrahedron.

  • The tetrahedron, having four equilateral triangles as faces.

    Bygone Beliefs H. Stanley Redgrove
  • Its head was a pyramid, a tetrahedron; its length vanished in the further darkness.

    The Metal Monster A. Merritt
  • It occurs crystallized in the form of the tetrahedron, also massive and disseminated.

  • Round Mars describe a tetrahedron; the sphere including this will be Jupiter.

    Kepler Walter W. Bryant
  • There were characters in Nansalese at each point of the tetrahedron, and other characters engraved in a circle around it.

    Islands of Space John W Campbell
  • These give the solid angles of the tetrahedron, the octahedron and the icosahedron.

  • From the sides of the hollow square sprang long arms of spheres, each tipped by a tetrahedron.

    The Metal Monster A. Merritt
  • Each of the four depressed areas forms a side of our tetrahedron and is occupied by an ocean.

    The Red Man's Continent Ellsworth Huntington
  • This four dimensional figure may be generated by moving the tetrahedron in the direction of the fourth dimension, as in Fig. 12.

    The Mystery of Space Robert T. Browne
British Dictionary definitions for tetrahedron


noun (pl) -drons, -dra (-drə)
a solid figure having four plane faces. A regular tetrahedron has faces that are equilateral triangles See also polyhedron
any object shaped like a tetrahedron
Derived Forms
tetrahedral, adjective
tetrahedrally, adverb
Word Origin
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
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Word Origin and History for 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).

Online Etymology Dictionary, © 2010 Douglas Harper
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tetrahedron in Science
Plural tetrahedrons or tetrahedra
A polyhedron having four faces.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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