| Acronym | Definition |
|---|
| MCI | Microwave Communications Incorporated |
| MCI | Mild Cognitive Impairment |
| MCI | Medical Council of India |
| MCI | Management Center Innsbruck (educational institution; Austria) |
| MCI | Mass Casualty Incident |
| MCI | Marine Corps Installations |
| MCI | Media Control Interface |
| MCI | Michigan City (Amtrak station code; Michigan City, IN) |
| MCI | Methylchloroisothiazolinone (preservative) |
| MCI | Marine Corps Institute |
| MCI | Millicuries |
| MCI | Mitsui Chemicals, Inc. (Japan) |
| MCI | Maryland Correctional Institution |
| MCI | Multi Channel Integration |
| MCI | Multi Card Imager |
| MCI | Multiport Communication Interface |
| MCI | Media Card Imager |
| MCI | Multimedia Control Interface |
| MCI | Multimedia Card Interface |
| MCI | Message Channel Interface |
| MCI | Modeling Clipping Indicator |
| MCI | Microwave Communications Inc. |
| MCI | Manufacturers Components Incorporated (Pompano Beach, FL) |
| MCI | Monetary Conditions Index |
| MCI | Mazda Canada, Inc. (Ontario, Canada) |
| MCI | Monte Carlo Integration (mathematics) |
| MCI | MassMutual Corporate Investors (USA) |
| MCI | Multi-Channel Integration |
| MCI | Mountaineering Council of Ireland |
| MCI | Multiple-Casualty Incidents (emergency medicine) |
| MCI | Massachusetts Correctional Institution |
| MCI | Mercy Corps International (non-profit international humantarian relief and development organization; Portland, Oregon, USA) |
| MCI | Management Charter Initiative |
| MCI | Marine Casualty Investigation |
| MCI | Motor Coach Industries Int'l, Inc. |
| MCI | Midwest Communications, Inc. (radio stations) |
| MCI | Mitsubishi Cable Industries, Ltd. (Japan) |
| MCI | Mortgage Credit Institution |
| MCI | Malicious Call Identification |
| MCI | Mobile Company of Iran (state-owned telecommunications company) |
| MCI | Management Concepts, Inc. |
| MCI | Massachusetts Correctional Institute |
| MCI | Macroinvertebrate Community Index |
| MCI | Multiplex Configuration Information |
| MCI | Montreal Chest Institute |
| MCI | Message Center Interface |
| MCI | Meal, Combat, Individual |
| MCI | Manejo Costero Integrado (Spanish: Integrated Coastal Management) |
| MCI | Magazine Circuit Industriel (French: Industrial Circuit Magazine) |
| MCI | Multi Colour Impression (stamps) |
| MCI | Mitsubishi Chemical Infonics Pte. Ltd. (Singapore) |
| MCI | Ministerio de Ciencia e Innovacion (Spanish) |
| MCI | Multi-Cluster Interleaving (data retrieval) |
| MCI | Kansas City, MO, USA - Kansas City International Airport (Airport Code) |
| MCI | Music Center, Inc (audio recording consoles) |
| MCI | Measurement Layer Interface (UMA) |
| MCI | Meetings, Conventions and Incentives |
| MCI | Multimedia Command Interface |
| MCI | Martingrove Collegiate Institute (Toronto, ON, Canada) |
| MCI | Malleable Cast Iron |
| MCI | Managing Criminal Investigations (criminal justice) |
| MCI | Multi-Command Instruction (military) |
| MCI | Modern Comptrollership Initiative (Canada) |
| MCI | McIntyre Media Ltd (Canada) |
| MCI | Man Crush Index (fantasy football) |
| MCI | Motorcycle Competition, Inc. |
| MCI | Malvern Collegiate Institute |
| MCI | Media Card Interface |
| MCI | Managed Cost Improvement |
| MCI | Mission Capability Inspection |
| MCI | Magnetic Current Imaging |
| MCI | Manufacturing Control Instruction |
| MCI | Mississippi Certified Investigator |
| MCI | Military Customs Inspection / Inspector |
| MCI | Mass Communications, Incorporated |
| MCI | Master Configuration Index (software documentation) |
| MCI | Maintenance and Control Interface |
| MCI | Major Currencies Index (Federal Reserve) |
| MCI | Material Condition Index |
| MCI | Material Control Index |
| MCI | Mass Centering Inertia (physics) |
| MCI | Metals Consulting International Limited (UK-based steel and metals management consulting firm) |
| MCI | Message Communication Interface (Unit) |
| MCI | Mid-Columbia Insurance |