hypervisor
n.— «In virtual machine parlance, the hypervisor is the layer of software that sits just “above” the hardware and handles the virtualization process (making one machine look like more than one machine and allowing each of those “virtual’ machines to run different operating systems).» —“Etymology of ‘hypervisor’ surfaces” by David Berlind ZDNet.com Aug. 10, 2005. (source: Double-Tongued Dictionary)