Definition of octahedron in English:


Syllabification: oc·ta·he·dron
Pronunciation: /ˌäktəˈhēdrən

noun (plural octahedrons or octahedra /-drə/)

  • 1A three-dimensional shape having eight plane faces, especially a regular solid figure with eight equal triangular faces.
    More example sentences
    • These are often known as the Platonic solids: the tetrahedron, cube, octahedron, dodecahedron and icosahedron.
    • These five remarkable solids - tetrahedron, cube, octahedron, dodecahedron, icosahedron - have faces that are congruent equilateral polygons.
    • Plato believed that atoms have the shapes of regular polyhedra: cubes, tetrahedrons, octahedrons, and so on.
  • 1.1A body, especially a crystal, in the form of a regular octahedron.
    More example sentences
    • Earth was a cube, air an octahedron, fire a tetrahedron and water an icosahedron.
    • The fluorite tends to occur only as cubes modified by the dodecahedron, with simple cubes or octahedra uncommon or absent.
    • Water was an icosahedron, and air had to be an octahedron.



More example sentences
  • It's octahedral in shape with a high, vaulted ceiling and sunlight streaming through hidden windows.
  • The outer portion of the garnets is altered to clinochlore, and small octahedral crystals of magnetite and martite occur in the schist.
  • In 1990 bright emerald-green, transparent, octahedral fluorite crystals were discovered in the Kettle mine by mine surveyor Michelle Scott.


late 16th century: from Greek oktaedron, neuter (used as a noun) of oktaedros 'eight-faced'.

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