trisoctahedron

noun

tris·​oc·​ta·​he·​dron ˌtri-ˌsäk-tə-ˈhē-drən 

: a solid (such as a crystal) having 24 congruent faces meeting on the edges of a regular octahedron

Word History

Etymology

Greek tris thrice + English octahedron — more at ter-

First Known Use

circa 1847, in the meaning defined above