"Monoblock" or "the primordial monoblock" is a term for the presumed state of the presumed material comprising the presumed universe just before it presumably exploded. Everything, no exceptions, including space itself, all in one tiny... something, (tiny with respect to... something), that did.... something, and then [waves hands] Big Bang! Try this google search.
Science can trace the expansion of the universe backwards quite a ways, within the bounds of our understanding of physics as it stands and it makes sense, albeit some very strange and difficult to swallow sense. But go back far enough, and a point is reached where our physics simply do not serve to describe the previous state. At all.
I liken it to tracing a pitched ball backwards, not having been around to witness the pitch, but analyzing the arc of its trajectory and theorizing that the ball erupted spontaneously from the ground in order to arrive where it is. We can't account for such a spontaneous emission, but after all, hey, there's the ball, right? The immediate and obvious objection is that "but physics tells us that can't happen"... well, physics tells us the exact same thing about the big bang. That's why I consider the comparison apt.
I'm not saying the big bang theory is wrong; I'm just saying it is definitely unproven, and that there are severe and fundamental problems with attempts to prove it at this time. Tomorrow, we have new physics, and that may resolve everything very nicely. But until or unless that happens -- until someone shows how the "ball could erupt from the dirt, spontaneously or otherwise" -- personally, I'm reserving BB theory acceptance.