= multi-user virtual environment
Example: Second Life
From the Wikipedia:
"MUVE (plural MUVEs) refers to online, multi-user virtual environments, sometimes called virtual worlds. While this term has been used previously to refer to a generational change in MUDs, MOOs, and MMORPGs, it is most widely used to describe MMOGs that are not necessarily game-specific. The term was first used in Chip Morningstar's 1990 paper The Lessons of Lucasfilm's Habitat. A number of the most popular and well-known MUVEs are listed below, although there are a number of others. Modern MUVEs have 3D isometric/third-person graphics, are accessed over the Internet, allow for some dozens of simultaneous users to interact, and represent a persistent virtual world.
Habitat (1987) and Club Caribe (1988) could be considered the first graphical MUVEs." (http://en.wikipedia.org/wiki/MUVE)