  There is no generally accepted definition for a virtual world, with many
complimentary terms and acronyms having emerged implying a virtual world.
Advances in systems architecture techniques such as, host migration of
instances, mobile ad-hoc networking, and distributed computing, bring in to
question whether those architectures can actually support a virtual world.
Without a concrete definition, controversy ensues and it is problematic to
design an architecture for a virtual world. Several researchers provided a
definition but aspects of each definition are still problematic and simply can
not be applied to contemporary technologies. The approach of this article is to
sample technologies using grounded theory, and obtain a definition for a
`virtual world' that is directly applicable to technology. The obtained
definition is compared with related work and used to classify advanced
technologies, such as: a pseudo-persistent video game, a MANet, virtual and
mixed reality, and the Metaverse. The results of this article include: a break
down of which properties set apart the various technologies; a definition that
is validated by comparing it with other definitions; an ontology showing the
relation of the different complimentary terms and acronyms; and, the usage of
pseudo-persistence to categories those technologies which only mimic
persistence.
