- (chemistry) 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.
- (US military) Military Airlift Command, one of three former divisions of the airforce, the others being SAC and TAC.
- (computing) Media access control: that 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.
- (computing) 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 a single cycle. Used extensively in implementations of digital filters, transforms and codecs.
- (mechanics) Mean Aerodynamic Chord.
- (cryptography) Message Authentication Code.
- (science fiction) magnetic accelerator cannon
- (Britain, telecommunications) Migration Authorisation Code.
- (immunology) Membrane Attack Complex, a part of the complement system of the innate immune system.