-parallelopiped-

n. [ Gr. para`llhlos parallel + 'epi`pedon a plane surface, 'epi`pedos on the ground, or level with it, level, flat; 'epi` on + pe`don the ground: cf. F. parallélopipède. ] (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.
Syn. -- parallelepiped, parallelepipedon, parallelopipedon. [ 1913 Webster ]