Mac OS(redirected from Apple Macintosh operating system)
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Mac OS(1) (macOS) The rebranding of Apple's Mac operating system starting with Sierra Version 10.12 in 2016. Sierra is "macOS Sierra" rather than Mac OS X Sierra. See Sierra.
(2) (Mac OS) (MACintosh Operating System) The original name of the operating system used in Apple's Macintosh computers and servers. Since its introduction in 1984, Mac operating systems have been written for three hardware lines: Motorola, PowerPC and Intel. See Macintosh and operating system.
Original Mac OS Designations
Apple used System 1 through System 7 designations for its Mac operating systems until 1997, when Version 8 was named Mac OS 8. OS 8 was superseded by OS 9 in 1999 and followed by OS 10 (OS X) in 1999 and 2001 for the server and desktop versions respectively. The Mac OS X moniker was maintained throughout subsequent versions with each new release given an animal name, such as Tiger and Leopard, and starting with Mac OS X 10.9, a location in California, such as Mavericks and Yosemite. In 2016, Version 10.12, the Mac OS X name was replaced with macOS. See Mac OS X.