Source : Webster's Revised Unabridged Dictionary (1913)

Parallelopiped \Par`al*lel`o*pi"ped\, n. [Gr. ? a body with
   parallel surfaces; ? parallel + ? a plane surface, ? on the
   ground, or level with it, level, flat; ? on + ? the ground:
   cf. F. parall['e]lopip[`e]de.] (Geom.)
   A solid, the faces of which are six parallelograms, the
   opposite pairs being parallel, and equal to each other; a
   prism whose base is a parallelogram.

Source : WordNet®

parallelopiped
     n : a prism whose bases are parallelograms [syn: {parallelepiped},
          {parallelepipedon}, {parallelopipedon}]