Computers and electronics

• MapInfo Interchange Format
  MapInfo Interchange Format
  MapInfo Interchange Format is a map and database exporting file format ofMapInfo software product. The MIF-file filename usually ends with .mif-suffix.Some MIF-files also have a related MID-file. The filename of a MID-file usually ends...
  
  ; .mid is also sometimes used as the filename extension for some MapInfo files
• Media Identification Code
  Media Identification Code
  The Media IDentification code is used on DVD-R, DVD+R and DVD-RAM discs to identify the manufacturer and to assist the DVD burner to select the best write strategy for the inserted media...
  
   (MID code), a code indicating the manufacturer of a DVD
• Mobile Internet device, a category of mobile computer
• Molded Interconnect Device
  Molded Interconnect Device
  A Molded Interconnect Device is an injection molded thermoplastic part with integrated electronic circuit traces. The use of high temperature thermoplastics and their structured metallization opens a new dimension of circuit carrier design to the electronics industry....
  
  , an injection molded thermoplastic part with integrated electronic circuit traces
• Multiple interface declaration, a construct in some computer programming language
  Programming language
  A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
  
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• Musical Instrument Digital Interface
  Musical Instrument Digital Interface
  MIDI is an industry-standard protocol, first defined in 1982 by Gordon Hall, that enables electronic musical instruments , computers and other electronic equipment to communicate and synchronize with each other...
  
  : .mid is sometimes used as an alternate filename extension for MIDI files

Medicine and biology

• Multi-infarct dementia
  Multi-infarct dementia
  Multi-infarct dementia is one type of vascular dementia. Vascular dementia is the second most common form of dementia after Alzheimer's disease in older adults. Multi-infarct dementia is thought to be an irreversible form of dementia, and its onset is caused by a number of small strokes or...
  
  , a disease also known as vascular dementia
• Monocyte
  Monocyte
  Monocytes are a type of white blood cell and are part of the innate immune system of vertebrates including all mammals , birds, reptiles, and fish. Monocytes play multiple roles in immune function...
  
  , a type of white blood cell in the innate immune system of vertebrates

Military

• Maritime identification digits, a 3-digit code identifing the country of a ship/coastal station using communication equipment.
• Mentioned in Despatches, a military award for gallantry or otherwise commendable service
• Militarized Interstate Disputes
  Militarized Interstate Disputes
  Militarized Interstate Disputes are conflicts between states that do not involve a full scale war. A conflict is described as an MID if it causes fewer than 1000 deaths, and some military force is used. This can be nothing more than a military display of force with no deaths...
  
  , conflicts between states that do not involve full-scale wars
• Military Intelligence Division
  Military Intelligence Division
  The Military Intelligence Division was a military intelligence branch of the United States Army, established in 1885. It was the first standing intelligence agency of the Army; the Union Army had had a Bureau of Military Information, but that had reported to the Commanding General for less than a...
  
  , a former military intelligence branch of the United States Army

Other

• Integration and Development Movement
  Integration and Development Movement
  The Integration and Development Movement or MID is a political party in Argentina.-Historical overview:Flying to Caracas, Venezuela in 1956, Argentine wholesaler and publisher Rogelio Frigerio secretly negotiated an agreement between his friend, the centrist UCR's 1951 vice-presidential nominee...
  
   (MID), a political party in Argentina
• Manuel Crescencio Rejón International Airport
  Manuel Crescencio Rejón International Airport
  Manuel Crescencio Rejón International Airport, formerly known as Mérida-Rejón Airport is an international airport located in the Mexican city of Mérida, Yucatán...
  
  , with IATA airport code MID
• Measuring Instruments Directive
  Measuring instruments directive
  The Measuring Instruments Directive is a directive by the European Union, which intends to create a common market for measuring instruments across the 27 countries of the EU...
  
  
• MID (Masters In Distance), an Estonian alternative pop band
• Mid vowel
  Mid vowel
  A mid vowel is a vowel sound used in some spoken languages. The defining characteristic of a mid vowel is that the tongue is positioned mid-way between an open vowel and a close vowel...
  
  
• Midfielder
  Midfielder
  A midfielder is an association football position. Some midfielders play a more defensive role, while others blur the boundaries between midfielders and forwards. The number of midfielders a team uses during a match may vary, depending on the team's formation and each individual player's role...
  
  , a position in association football (soccer)
• Motor Insurance Database, in the UK is a central database of vehicles that have a current and valid motor insurance policy
• Russian Ministry of Foreign Affairs, for which MID is a colloquial term