tetrahedroid

from The Century Dictionary.

• Resembling a tetrahedron.
• noun A quartic surface the envelop of a quadric surface touching eight given lines; a surface obtained by a homographic transformation of the wave-surface; a Kummer's surface whose sixteen nodes lie in fours upon the faces of a tetrahedron through whose summits the sixteen double planes pass by fours; a quartic surface cut by each of the planes of a tetrahedron in pairs of conics in respect to which the three summits in this plane are conjugate points, and such that one of the points of intersection of the conics (and therefore all) is a node of the surface: so named by Cayley in 1846.