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icosahedron

[ahy-koh-suh-hee-druh n, ahy-kos-uh-] /aɪˌkoʊ səˈhi drən, aɪˌkɒs ə-/
noun, plural icosahedrons, icosahedra
[ahy-koh-suh-hee-druh, ahy-kos-uh-] /aɪˌkoʊ səˈhi drə, aɪˌkɒs ə-/ (Show IPA)
1.
a solid figure having 20 faces.
Origin of icosahedron
1560-1570
1560-70; < Greek eikosáedron, equivalent to eikosa- (variant of eikosi-, combining form of eíkosi twenty) + -edron -hedron
Related forms
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for icosahedron
Historical Examples
• The icosahedron, having twenty equilateral triangles as faces.

H. Stanley Redgrove
• Associated words: vicenary, vigesimal, vigesimation, icosahedron.

Louis A. Flemming
• These give the solid angles of the tetrahedron, the octahedron and the icosahedron.

• Within the earth's orbit inscribe an icosahedron: the sphere inscribed in it will be Venus's orbit.

John Elliot Drinkwater Bethune
• Now, inscribe in the Earth an icosahedron, the circle inscribed in it will be Venus.

John Elliot Drinkwater Bethune
• An icosahedron is a figure comprehended under twenty equal sides.

Robert T. Browne
• That for the tetrahedron has 12 for its order, for the cube (or octahedron) 24, and for the icosahedron (or dodecahedron) 60.

• Then inscribe in the Earth an icosahedron; the circle described in it will be Venus.

• Two of these generate the cube and the octahedron; five of these generate the dodecahedron and the icosahedron.

Annie Besant and Charles W. Leadbeater
British Dictionary definitions for icosahedron

icosahedron

/ˌaɪkəsəˈhiːdrən/
noun (pl) -drons, -dra (-drə)
1.
a solid figure having 20 faces. The faces of a regular icosahedron are equilateral triangles
Derived Forms
Word Origin
C16: from Greek eikosaedron, from eikosi twenty + -edron-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 icosahedron
n.

1560s, from Greek eikosahedron, neuter of eikosahedros, from eikosi "twenty" + -hedra "seat, base, chair, face of a geometric solid," from PIE root *sed- (1) "to sit" (see sedentary). Greek eikosi is from PIE *wikmti- "twenty," from *wi- "in half," hence "two" + (d)kmti-, from root *dekm- "ten" (see ten).

Online Etymology Dictionary, © 2010 Douglas Harper
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icosahedron in Science
 icosahedron   (ī-kō'sə-hē'drən)    Plural icosahedrons or icosahedraA polyhedron having twenty faces.icosahedral adjective
The American Heritage® Science Dictionary