polyhedron

noun3

1. •
   A solid figure with many flat faces and straight edges.

   • Of the convex polyhedra with regular faces, the only ones that have tetrahedral, octahedral, or icosahedral symmetry are the Platonic and Archimedean solids. — 1966
2. •
   A stage in the growth of Hydrodictyon, when the resting spore breaks up into several megazoospores that put out horn-like appendages; these polyhedra break up into zoospores.
3. •
   A polyscope, or multiplying glass.