American Heritage Dictionary of the English Language, 5th Edition
Prismoid Sentence Examples
If R and S are the ends of a prismoid, A and B their areas, h the perpendicular distance between them, and C the area of a section by a plane parallel to R and S and midway between them, the volume of the prismoid is *h(A+4C+B).
The most instructive is to regard the prismoid as built up (by addition or subtraction) of simpler figures, which are particular cases of it.
(iv) For the prismoid in general let ABCD ...
Then the prismoid is divided into a pyramid with vertex P and base ABCD ..., and a series of tetrahedra, such as PABa or PAab.
By (i) and (iii), the formula holds for each of these figures; and therefore it holds for the prismoid as a whole.