noun

• (US, informal) Used to address a man whose name is unknown.
• A diminutive of the male given name Max.
• (US, Canada) A diminutive for a person with a surname that starts with "Mac" or "Mc".
• A Macintosh computer (made by Apple Inc.).
• (informal) McMaster University
• (Singapore, slang) McDonald's
• Clipping of mackintosh (“a raincoat”). [A waterproof long coat made of rubberized cloth.]
• (Canada, US, slang) Clipping of macaroni. [(uncountable) A type of pasta in the form of short tubes; sometimes loosely, pasta in general.]
• (US military) Acronym of Military Airlift Command, formerly, one of three former divisions of the US airforce, the others being SAC and TAC.
• Acronym of Military Armament Corporation.
• (UN) Initialism of Military Armistice Commission.
• (chemistry) Initialism of maximum allowable concentration, the maximum concentration of a pollutant which is considered harmless to healthy adults during their working hours, assuming they breathe uncontaminated air at all other times.
• (computer security) Initialism of mandatory access control.
• (networking) Initialism of media access control: the portion of Ethernet, Wi-Fi 802.11 wireless, Bluetooth, FDDI, ATM, and Fibre Channel networks that controls which hardware devices have access to the media over which signals are sent.
• (aviation) Initialism of mean aerodynamic chord.
• (aviation) Initialism of mid-air collision.
• (cryptography) Initialism of message authentication code.
• (military, nautical, aviation, historical) Initialism of merchant aircraft carrier.
• (science fiction) Initialism of magnetic accelerator cannon.
• (UK, telecommunications) Initialism of Migration Authorisation Code.
• (immunology) Initialism of membrane attack complex, a part of the complement system of the innate immune system. [(immunology) A structure, typically formed on the surface of a pathogen cell membrane as a result of the activation of the host's complement system, creating transmembrane channels that disrupt the cell membrane, leading to cell lysis and death.]
• (computing) Initialism of multiply and accumulate, a hardware module found in digital signal processors which performs a multiplication and adds the result of that operation to an accumulator in the same cycle, used extensively in implementations of digital filters, transforms, and codecs.
• (microbiology) Initialism of Mycobacterium avium complex.
• (anesthesiology) Initialism of minimum alveolar concentration.
• (anesthesiology) Initialism of monitored anesthesia care.