Just a name for everything, for the all encompassing set. It is in our nature to name things and this is a name to include all names. Whenever one talks or thinks about anything that thing is inside it. No exceptions, none, zip. It represents the top most level of ThisWriter's Cosmology as defined here on this wiki. It has been referred by many other names like Reality, Omniverse, The Box, etc but here the name Omniumverse was chosen. These names may also plausibly refer to things that have been named differently in this Cosmology.