The term "OS virtualisation" is just fine here -- it refers to the support required to virtualise an operating system, which conventionally means the device driver, scheduler and memory interfaces. Providing such a layer lets any reinterpretation of "OS" still run above it.
Container-based technologies are far more nebulous in their definition, since it covers individual operating system concepts that don't quite migrate across distributions. FreeBSD jails, Solaris zones, LXC, MacOS X app sandboxes are all container-based virtualisation, but differ greatly in their details and specific interfaces.