virtual memory 
(also virtual storage)
noun [mass noun] Computing
Memory that appears to exist as main storage although most of it is supported by data held in secondary storage, transfer between the two being made automatically as required.By introducing integers into memory lookups, more precision is gained, enabling more flexibility in storing graphics data in places such as virtual memory or main system memory....
- Block-level storage virtualization distributes blocks of data to virtual storage pools across multiple storage devices, which helps to manage space and control devices at the hardware level.
- I haven't run out of memory in more than a decade, ever since virtual memory appeared in Windows 386.