Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.


The name of Apple's Unix-based operating system for Mac desktop and laptop computers. macOS is a continuation of the Mac OS X operating system, which was rebranded as macOS starting with the Sierra version in 2016.

Since its introduction in 1984, the Mac operating system has had five brand names (see below) and was designed to work with four hardware lines: Motorola, PowerPC, Intel and ARM. See Motorola, PowerPC, Intel Mac, Apple M1, macOS server and Mac computer.

Name Evolution
The Mac originally used "System" designations for its operating system, which then became "Mac OS." Starting in 1999, Mac OS X was a major upgrade that was branded with animal names followed by places in California (see Mac OS X).

YearIntro.  Name       Versions

  2021   "macOS"     12.0    Monterey
  2020   "macOS"     11.0    Big Sur
  2019   "macOS"     10.15   Catalina
  2018   "macOS"     10.14   Mojave
  2017   "macOS"     10.13   High Sierra
  2016   "macOS"     10.12   Sierra

  2013   "OS X"      10.9 to 10.11

  1999   "Mac OS X"  10.0 to 10.8

  1995   "Mac OS"    7.6 to 9.2

  1984   "System"    1 to 7.5

Long Live the Mac Operating System
Introduced in 1999, Mac OS 8.6 was the first time the version number appeared on the Mac startup screen. Two years earlier, Mac OS 8.0 was the largest update to the Mac operating system since System 7.
Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
References in periodicals archive ?
Following the emphasis that Apple gave to Metal API, Parallels made significant investments to ensure excellent DirectX 11 performance on Metal in macOS Mojave and macOS Catalina (10.15), in addition to DirectX 10 and 9.
As seen on the ( macOS Reddit , many users are dissuading other users from using the macOS Catalina immediately.
Version 19 also adds support for Apple's Dark Mode that was introduced in macOS Mojave.
With macOS Catalina, Apple is introducing new assistive technologies to help every user get the most out of their Mac.
If you have any of the above machines, you can get your dirty mitts on the newest (and definitely buggy) MacOS Catalina public beta.
Apple has recently previewed macOS Catalina, the latest version of the its desktop operating system, at the company's annual Worldwide Developers Conference held in San Francisco.
The new NCP Secure macOS Clients provide enhanced security including fingerprint authentication, said Patrick Oliver Graf, CEO of NCP engineering.
"macOS Mojave is a major update that introduces powerful new features for a wide range of Mac users, from consumers to pros," said Craig Federighi, Apple's senior vice president of software engineering.
in macOS Mojave with an all-new Gallery View that lets users skim through files
Macos started his the fourth and last chukker with a field goal to reduce the margin to 6-3.
DP/Guard Rice's Macos Araya then started playing aggressive polo and pumped in a field goal to reduce the margin to 4-2.