z/OS <operating system> An {operating system} from {IBM}. According to IBM, it is a secure, scalable, high-performance enterprise operating system on which to build and deploy Internet and {Java}-enabled applications, providing a comprehensive and diverse application execution environment. (http://ibm.com/servers/eserver/zseries/zos/). (2008-01-22)
ZOS Z/Operating System (IBM, Java, OS), "z/OS"