PRISM, in Geometry, is a solid body, the two ends of which are any plane figures which are parallel, equal, and similar; and its sides, connecting those ends, are parallelograms.
PRISMOID is a solid body, somewhat resembling a prism, but its ends are any dissimilar parallel plane figures of the same number of sides, the upright sides being trapezoids. If the ends of the prismoid be bounded by dissimilar curves, it is sometimes called a cylindroid.