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penta- (five) +‎ -choron (room), from Ancient Greek πέντε (pénte, five) and χώρος (khṓros, room).


pentachoron (plural pentachorons or pentachora)

  1. (mathematics) A four-dimensional object equivalent to a tetrahedron, constructed out of five tetrahedra.
    • 2008, George Musser, The Complete Idiot's Guide to String Theory, page 174:
      A triangle becomes a tetrahedron (a type of pyramid), then a pentachoron (a hyperpyramid).
    • 2008, Prabhakar Gupta et al., Design and Analysis of Algorithms, page 356:
      Geometrically, K3 relates to a triangle, K4 a tetrahedron, K5 a pentachoron, etc.
    • 2013, Caspar Henderson, The Book of Barely Imagined Beings, page 7:
      The tetrahedron is a 3-simplex whose 4-simplex analog is the pentachoron, a four-dimensional body which can be orphographically [sic] projected onto a quincrux (as well as a pentagram and other shapes).