Antiprism
The Century Dictionary and Cyclopedia
noun.
An auxiliary prism; part of a compound prism placed with its refractive edge in a reversed position.
Wiktionary, Creative Commons Attribution/Share-Alike License
noun.
A
polyhedron
composed of two
parallel
copies of some particular
polygon
, connected by an
alternating
band of
triangles
.
Word Usage
"But math-crazy Lovecraft would have known that a trapezohedron is an "antiprism.""