os

OS

(O' es') n.

1. operating system.

2. any of various IBM mainframe operating systems, early versions of OS/390.

3. open source.

OS/2

(O' es' tOO') n.

an operating system published by IBM, developed for use on its PS/2 line of computers and other desktop computers, designed to have a high degree of compatibility with MS-DOS.

OS/390

(O' es' thrE' nIn' ti) n.

a mainframe operating system published by IBM, the predecessor of z/OS.