hexahedron
noun
hexa·he·dron ˌhek-sə-ˈhē-drən 
plural hexahedrons also hexahedra ˌhek-sə-ˈhē-drə
: a polyhedron of six faces (such as a cube)
Word History
Etymology
Late Latin, from Greek hexaedron, from neuter of hexaedros of six surfaces, from hexa- + hedra seat — more at sit
First Known Use
1571, in the meaning defined above