You call it a vase, hollow form, or vessel. That seems to be the biggest defining factor.
Vase, anything you call a vase.
Hollow form, any form that is hollow
Vessel, what you burst in your head trying to figure out how to define vase or hollow form. :cool2:
There are actually some more detailed definitions out there but folks generally just ignore them and call a piece what they feel is the best description. I tend to like vase myself. I save hollow form for weird stuff and never use vessel.
Dietrich