| Mathematics Education Collaborative | Academic & Science |
| Mecklenburg Electric Cooperative | Academic & Science |
| Middle East College | Academic & Science |
| Microbial Electrolysis Cell | Academic & Science |
| Medical Education Center | Academic & Science |
| Mississippi Electronic Courts | Academic & Science |
| Mayville Engineering Co | Academic & Science |
| Manta | Airport Code |
| Mutual Execution of Contract | Business |
| Mediterranean Exploration Company | Business |
| Metro Exhibit Corporation | Business |
| Mercado Electrónico Continuo | Business |
| Midamerican Energy Holdings Company | Business |
| Mountain Equipment Company | Business |
| Mayville Engineering Company | Business |
| Marginal External Cost | Business |
| Mobile Entertainment Center | Business |
| Manufacturing, Engineering, and Construction | Business |
| Mountain Equipment Company Vietnam | Business |
| Mecom Group | Business |
| Mountain Equipment Co. | Business |
| Malaysia Electric Corporation | Business |
| Marianas Energy Corporation | Business |
| Most Efficient Chemistry | Chemistry |
| Management Excellence Community | Community |
| Michigan Environmental Council | Community |
| MacMillan English Campus | Community |
| Mountain East Conference | Community |
| Metropolitan Educational Council | Community |
| Microsoft Exchange Conference | Community |
| Medical Education Collaborative | Community |
| Merrimack Education Center | Community |
| Mechanical Electronics and Computing | Computing |
| Master Electronic Corporation | Computing |
| Mobile Equipment Console | Computing |
| Multiple Ethernet Cable | Computing |
| Multichassis Etherchannel | Computing |
| Media Expansion Card | Computing |
| Multi-Access Edge Computing | Computing |
| Memory Efficient Convolution | Computing |
| Microsoft Enterprise Cube | Computing |
| Master Event Collector | Computing |
| Mobile Edge Computing | Computing |
| Microsoft Experience Center | Computing |
| Megacoin | Cryptocurrency |
| Medgar Evers College | Educational Institute |
| Maximus Mecca Source File | File Type |
| Matter in Extreme Conditions | General |
| Macro Expansion Counter | General |
| Malawi electoral commission | General |
| Medical Electronic Construction | General |
| Modeling Experiment and Computation | General |
| Most Expensive Cars | General |
| Middle European Championship | General |
| Modular Energy Carrier | General |
| Matra Enthusiasts Club | General |
| Messerschmitt Enthusiasts Club | General |
| Michigan Eclipse Club | General |
| Motronic Engine Control | General |
| Mid Engined Car | General |
| Mise En Circulation | General |
| Motor Electronics Coolant | General |
| Mobile Education Centre | General |
| Mitsubishi Eclipse Cross | General |
| Motor Enthusiasts Club | General |
| Mopar Express Care | General |
| Many Enemas Coming | General |
| Middle East Center | General |
| Middle Eastern Cinemas | General |
| Missouri Ethics Commission | General |
| Miami Entrepreneurship Center | General |
| Minimal Effective Concentration | General |
| Mobile Engagement Center | General |
| Manufacturing Exploration and Combat | General |
| Materials Energy and Constructions | General |
| Minimum Essential Coverage | General |
| Massively Empowered Classrooms | General |
| Member of the Executive Council | Governmental |
| Medical Employment Classification | Governmental |
| Midwest Environmental Control | Governmental |
| Model European Council | Governmental |
| Master Executive Council | Governmental |
| Modified Endowment Contract | Governmental |
| Medical Eligibility Criteria | Governmental |
| Mack Energy Corporation | Governmental |
| Mississippi Economic Council | Governmental |
| Mack Energy Corp | Governmental |
| Metalsmith Chief Petty Officer | Governmental |
| Marine Employees Commission | Governmental |
| MERTA CITY | Indian Railway Station |
| Ministerio de Educación y Ciencia | International |
| Mercato Comune Europeo (European Economic Community) | International |
| Movimiento Emergent de Concordancia | International |
| Mecaz | International |
| Modeling, Experimentation, and Computation | Maths |
| Management Education for Clinicians | Medical |
| Management Executive Committee | Medical |
| mechlorethamine | Medical |
| meclofenamate | Medical |
| meconium | Medical |
| Median Effective Concentration | Medical |
| Middle Ear Canal | Medical |
| Mouse Embryo Cell | Medical |
| mucoepidermoid carcinoma | Medical |
| Minimum Effective Concentration | Military and Defence |
| Medium Endurance Cutter | Military and Defence |
| Middle East Coalition | Military and Defence |
| Maine Central Railroad (Pan Am Railways) | Regional |
| Medieval European Coinage | Regional |
| Mantra, Ecuador | Regional |
| Maine Central Railroad (later Guilford Transportation Industries, now Pan Am Railways) | Regional |
| Main Engine Controller | Space Science |
| Master Event Controller | Space Science |
| Materials Experiment Carrier | Space Science |
| Mission Events Controller | Space Science |
| Missouri Equine Council | Sports |
