pentachoron

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 analogous 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).

• 5-cell

• polychoron

• ctenophoran