Caldera
A caldera is a volcanic crater which usually has a flat surface, at the bottom, formed by the hardening of a lava lake.Yellowstone National Park is largely contained within the Yellowstone caldera.
Caldera Systems is a corporation initially associated with the Linux and open source movement; it changed its name in 2002 to "SCO Group". Lately SCO has been attempting to claim ownership of all operating systems that are related to UNIX. See SCO Group.
Notable Calderas