The Collaborative International Dictionary of English v.0.48:

mac \mac\ n.
   Shortened form of mackintosh, a waterproof raincoat made of
   rubberized fabric.

   Syn: mackintosh, mac, mack.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Mac \Mac\ prop. n.
   Shortened form of Macintosh, a brand name for a personal
   computer; as, the latest Mac has great new features.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Mac \Mac\ [Gael., son.]
   A prefix, in names of Scotch origin, signifying son.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mac
    n 1: a waterproof raincoat made of rubberized fabric [syn:
         macintosh, mackintosh, mac, mack]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MAC
       Mandatory Access Control (MLS, DAC)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MAC
       Media Access Control (ISO, OSI, LAN, , WLAN, ...)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MAC
       Membership Advisory Committee (ICANN)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MAC
       Message Authentication Code (SSL, SRT, cryptography)


The Free On-line Dictionary of Computing (30 December 2018):

Mac

    The line of computers manufactured by Apple Inc.
   "Mac" is not primarily a nickname or an abbreviation, but a
   brand name and trademark in its own right.  Apple currently
   (2009) refer to the brand as any of "Mac", "iMac" or
   "Macintosh" (all registered trademarks).

   The Mac was Apple's successor to the Lisa.  The project was
   proposed by Jef Raskin some time before Steve Jobs's
   famous visit to Xerox PARC.  Jobs tried to scuttle the
   Macintosh project and only joined it later because he wasn't
   trusted to manage the Lisa project.

   The Macintosh user interface was notable for popularising
   the graphical user interface, with its easy to learn and
   easy to use desktop metaphor.

   The first Macintosh, introduced in January 1984, had a
   Motorola 68000 CPU, 128K of RAM, a small monochrome
   screen, and one built-in floppy disk drive with an external
   slot for one more, two serial ports and a four-voice sound
   generator.  This was all housed in one small plastic case,
   including the screen.  When more memory was available later in
   the year, a 512K Macintosh was nicknamed the "Fat Mac."

   The Mac Plus (January 1986) added expandability by providing
   an external SCSI port for connecting hard disks, magnetic
   tape, and other high-speed devices.

   The Mac SE (March 1987) had up to four megabytes of RAM, an
   optional built-in 20 megabyte hard disk and one internal
   expansion slot for connecting a third-party device.

   The Mac II (March 1987) used the faster Motorola 68020 CPU
   with a 32-bit bus.

   In 1994 the Power Mac was launched, and in 1999 the iMac
   was introduced.  The SuperDrive appeared in the iMac in 2002.

   The Macintosh Operating System is now officially called "Mac
   OS".  Mac OS X is the successor to Mac OS 9, although its
   technological parent is the NEXTSTEP OS from Next, Inc.,
   founded by Steve Jobs after he left Apple the first time.  OS
   X is based largely on the BSD UNIX system.  The core of the
   OS X operating system is released as free source code under
   the project name Darwin.

   The standard Macintosh screen resolution is 72 dpi (making
   one point = one pixel), exactly half the 144 dpi
   resolution of the ancient Apple Imagewriter dot matrix
   printer.

   If "Macintosh" were an acronym, some say it would stand for
   "Many Applications Crash, If Not, The Operating System Hangs".
   While this was true for pre Mac OS 9 systems, it is less true
   for Mac OS 9, and totally incorrect for Mac OS X, which has
   protected memory, so even if one application crashes, the
   system and other applications are unaffected.

   See also Macintosh file system, Macintosh user interface.

   Apple Home (http://apple.com/mac).

   (2009-05-05)


The Free On-line Dictionary of Computing (30 December 2018):

MAC

   1. Media Access Control.

   2. Early system on Ferranti Mercury.  Listed in CACM
   2(5):16 (May 1959).