parallelepiped vs parallelopipedon

parallelepiped and parallelopipedon both are nouns.

Word	Noun	Adjective	Verb	Adverb
parallelepiped	Yes	No	No	No
parallelopipedon	Yes	No	No	No

As nouns, parallelepiped and parallelopipedon are synonyms defined as:

parallelepiped and parallelopipedon: a prism whose bases are parallelograms

Other synonyms of parallelepiped include parallelepipedon, parallelopiped.

parallelepiped (noun)	parallelopipedon (noun)
a prism whose bases are parallelograms	a prism whose bases are parallelograms