ico·​sa·​he·​dron (ˌ)ī-ˌkō-sə-ˈhē-drən How to pronounce icosahedron (audio)
plural icosahedrons or icosahedra (ˌ)ī-ˌkō-sə-ˈhē-drə How to pronounce icosahedron (audio)
: a polyhedron having 20 faces

Example Sentences

Recent Examples on the Web Fuller started by building icosahedral domes but realized that larger structures containing more than twenty triangles could be made by taking the primary triangles and systematically assembling them into larger triangles, each of which could then be used to build an icosahedron. Judith Graf, The New York Review of Books, 1 Dec. 2022 The symmetry group of the quasicrystal is the same as that of the regular 20-sided solid known as an icosahedron, and the chemistry is given by the formula Si61Cu30Ca7Fe2. David Bressan, Forbes, 18 May 2021 The arrangement of rotations which leave the objects looking unchanged is the same as that of a regular icosahedron. George Hart, Scientific American, 22 Mar. 2013 One popular design is based on the mathematical structure of an icosahedron, a three-dimensional shape built from equilateral triangles. Eugenia Cheng, WSJ, 19 Nov. 2020 Truly glorious, a 20-sided die, the icosahedron, goes back to antiquity. William Herkewitz, Popular Mechanics, 1 Sep. 2019 For that kind of math, the icosahedron was the ideal random number generator. William Herkewitz, Popular Mechanics, 1 Sep. 2019 The Florence specimen exhibited the symmetries of an icosahedron, a soccer-ball-like atomic arrangement that can be viewed from 60 different angles without any change to the structure’s overall orientation. Quanta Magazine, 13 June 2014 The immersive experience took place under a giant version of their icosahedron logo, which — Odesza explained in a Reddit thread — represents their genre and style versatility. Susie Schmank, Indianapolis Star, 30 Apr. 2018 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'icosahedron.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Greek eikosaedron, from eikosi twenty + -edron -hedron — more at vigesimal

First Known Use

1570, in the meaning defined above

Time Traveler
The first known use of icosahedron was in 1570

Dictionary Entries Near icosahedron

Cite this Entry

“Icosahedron.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/icosahedron. Accessed 8 Jun. 2023.

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