A VirtualMachine used to run InfocomCompany style TextAdventureGame (and also graphical ones, in some cases), such as ZorkGame.
Can also be referred to as either ZeeMachine (depending on your country of origin), or ZorkMachine (which was the original title, but has gone out of fashion).
GrahamNelson's InformLanguage compiler produces code files designed to run on the ZedMachine.
These creatures I think
Are called the Zeds.
They have one hair upon their heads.
It grows so fast
So fast they say
They need a haircut every day.
(DoctorSeuss?)