Prismoid

A polyhedron two faces of which (its bases) are located in parallel planes, while the other faces are triangles or trapeziums, and, moreover, such that one side of each triangle face (that is not a base) and the two bases of each trapezium face (that is not a base) are sides of the bases of the prismoid (cf. Fig.). The volume of a prismoid is

$$\frac h6(S+S'+4S''),$$

where $h$ is the distance between the bases, $S$ and $S'$ are their areas and $S''$ is the area of the intersection that has equal distance to both bases.

Figure: p074840a

Comments

In $d$-space a prismoid is the convex hull of two $(d-1)$-polytopes lying in two distinct parallel hyperplanes.

References

[a1]	B. Grünbaum, "Convex polytopes" , Wiley (1967)