parallelopiped vs parallelopipedon

parallelopiped and parallelopipedon both are nouns.

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

As nouns, parallelopiped and parallelopipedon are synonyms defined as:

parallelopiped and parallelopipedon: a prism whose bases are parallelograms

Other synonyms of parallelopiped include parallelepiped, parallelepipedon.

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