polylithism
<programming> A property of a data-object that can exist in
many shapes and sizes, but not simultaneously; which
distinguishes it from a {union}. It is often implemented as a
set of {classes} (or structs) derived from a common {base
class} (or with a common header, as in the case of structs),
typically without any {methods}.
It has been loosely described as {polymorphic} data.
[Clarification?]
(1996-01-07)