> I used to use parallelepiped in USA English until I retired in 1990,
> although I too sometimes used the word box for a rectangular one. I
> observed that the word parallelepiped had a humorous effect on many
> students, which encouraged me to use it even when something else would do.
> I wish now that I'd thought of telling students that if they found the word
> parallelepiped not to their liking, they could use parallelepipedon instead.
I think the funniness comes from the usual pronunciation, which makes
the word rhyme with "piped". I prefer the more logical pronunciation
that follows the meaning: "parallel-epi-ped". My students generally
manage to keep their faces straight when I say this!
John Conway