[colordrops]

When the term centralization is used, it refers to the idea that a single entity can control or damage a system through a single (central) point. How is that the case with bitcoin?

[davidgerard]

Er, no, it means a thing is centralising (which is observably the case). The word doesn't just refer to the limit case of a single entity.

And we have in fact had the single entity case, when GHash went over 51% (and had successfully conducted a 49% attack already), as you already know.