Open Peer Review on Qeios ## Tetrahedron National Cancer Institute ## Source National Cancer Institute. Tetrahedron. NCI Thesaurus. Code C63856. A tetrahedron is a geometric shape composed of a polyhedron with four faces.Open Peer Review on Qeios ## Tetrahedron National Cancer Institute ## Source National Cancer Institute. Tetrahedron. NCI Thesaurus. Code C63856. A tetrahedron is a geometric shape composed of a polyhedron with four faces.