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]

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]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006):

MAC
       Mandatory Access Control (MLS, DAC)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006):

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


V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006):

MAC
       Membership Advisory Committee (ICANN)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006):

MAC
       Message Authentication Code (SSL, SRT, cryptography)