Definition of Mac os x

Mac OS X (IPA: ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc., the latest of which is pre-loaded on all currently shipping Macintosh computers. Mac OS X is the successor to the original Mac OS, which had been Apple's primary operating system (OS) since 1984. Unlike its predecessors, Mac OS X is a Unix OS built on technology that had been developed at NeXT through the second half of the 1980s until Apple purchased the company in early 1997.