Definitions
from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A polyhedron with four faces.
from The Century Dictionary.
- noun A solid comprehended under four plane faces; especially, the regular tetrahedron, or triangular pyramid having its base and sides equilateral triangles.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Geom.) A solid figure inclosed or bounded by four triangles.
- noun (Geom.) a solid bounded by four equal equilateral triangles; one of the five regular solids.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun geometry a
polyhedron withfour faces; theregular tetrahedron, the faces of which are equalequilateral triangles , is one of thePlatonic solids .
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun any polyhedron having four plane faces
Etymologies
from The American Heritage® Dictionary of the English Language, 4th Edition
from Wiktionary, Creative Commons Attribution/Share-Alike License
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Examples
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A tetrahedron is a good model for e.g. a carbon atom in a molecular form, and the tighter the "packing," the tighter the molecular bonds.
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Otherwise known as a tetrahedron, a "Caltrop", or to a lesser degree "Ol' Pointy".
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Your tetrahedron could be our key to all the mysteries of Omegan science and history.
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In our space, four equidistant points can be located, the vertices of a tetrahedron, that is, a pyramid having four triangular faces.
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It will be seen that the tetrahedron is the fundamental form, the three-sided pyramid on a triangular base, _i. e._, a solid figure formed from four triangles.
Occult Chemistry Clairvoyant Observations on the Chemical Elements Annie Wood Besant 1890
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The tetrahedron is the form of chromium and molybdenum, but not that of the head of their group, oxygen, which is, like hydrogen, _sui generis_.
Occult Chemistry Clairvoyant Observations on the Chemical Elements Annie Wood Besant 1890
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Above the tetrahedron is a balloon-shaped figure, apparently drawn into shape by the attraction of the tetrahedron.
Occult Chemistry Clairvoyant Observations on the Chemical Elements Annie Wood Besant 1890
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A classic 3D fractal is the Sierpinski tetrahedron, which is a tetrahedron of tetrahedra of tetrahedra, etc.
MAKE Magazine Gareth Branwyn 2010
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Through them, one had a spec - tacular view across the river to the futuristic Flamme d'Or, the Phillippe Starke-designed building of black glass, a kind of tetrahedron on acid, surmounted by a vaguely flamelike shape derisively christened by Tokyoites "the Golden Turd."
Second Skin Lustbader, Eric 1995
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For the first prize in 1901 the Academy had to consider 20 nominations, but no less than 11 of these named van't Hoff, who was also chosen by the Committee for Chemistry. van't Hoff had already during his thesis work in Utrecht in 1874 published his suggestion that the carbon atom has its four valences directed towards the corners of a regular tetrahedron, a concept which is the very foundation of modern organic chemistry.
The Nobel Prize in Chemistry: The Development of Modern Chemistry 2010
classifiedinformation commented on the word tetrahedron
A polyhedron with four triangular sides.
Also known as the coolest shape in the world.
January 18, 2009
kewpid commented on the word tetrahedron
It is a pretty neat shape. But don't you find it a little pointy?
January 18, 2009
seanahan commented on the word tetrahedron
What? The coolest? The dodecahedron and icosahedron are way cooler.
January 19, 2009
rolig commented on the word tetrahedron
I wonder if Classifiedinformation is thinking of the special energy some new-age mysticists associate with pyramids.
January 19, 2009
sionnach commented on the word tetrahedron
Uri Geller gushes: "I haven't needed to buy a single razor blade since I discovered the healing aura of the tetrahedron right here in Area 51"
Uri touts the power of tetrahedrically enhanced razor blades
But I agree with seanahan, among the five Platonic solids, the dodecahedron and icosahedron are cooler.
If the pointiness becomes an issue, there is always the class of Johnson solids to consider. I don't know exactly what a gyroelongated pentagonal cupolarotunda (J47) looks like*, but I'd certainly make room for one right next to my metabidiminished rhombicosidodecahedron (J81) and my snub square antiprism (J85).
* OK, here's a picture: J47.gif
January 19, 2009