You almost inadvertently answered your own question there. Some current theories/speculation about the ultimate origin of the universe (i.e. the origins of everything that formed the matter and energy unleashed in the Big Bang) involve other dimensions.Where did the matter come from that resulted from the "Big Bang Therom?" What put it there and how did it get there? What was there before the so-called "Explosion that started the Universe?" How do we know that there are not other dimentions?
:Edit:
And on a more relevant note...
An oxymoron is an oxymoron, a concept with a defined and limited meaning. A human construct. Not something that can be redefined at whim. Deciding that you want to give the word a wider meaning is one thing, but that does not actually make it so. For example, I can't declare myself a gibbon and expect others to accept my redefinition of 'gibbon', regardless of any real or perceived similarities I might, or might not, have to said primate.