| Miami (ok) | Airport Code |
| Miclyn Express Offshore Limited | Business |
| Million/Millions | Business |
| Minco | Business |
| Management Information Office | Business Management |
| Module Input Output | Computer Assembly Language |
| Multimedia Information Organizer | Computing |
| My Input Output | Computing |
| Memory Input Output | Computing |
| Managed Input Output | Computing |
| Mask Input Output | Computing |
| Modular Input Output | Computing |
| Mobile I O | General |
| Mobile Ideal Original | General |
| More In One | General |
| Make it Own | General |
| Micaceous Iron Oxide | General |
| Maritime Interdiction Operations | General |
| Mandated Iwi Organisation | General |
| Micaeous Iron Oxide | General |
| Motility indole ornithine | General |
| Made in Oklahoma | General |
| My intelligent OrganizationMiO | General |
| Magnetic Iron Oxide | General |
| Many Independent Objective | General |
| Motivation Inspiration and Opportunity | General |
| Modular Individual Organised | General |
| Mediterranean Information Office for Environment, Culture, and Sustainable Development | Governmental |
| Marine Inspection Operations | Governmental |
| MOLISAR | Indian Railway Station |
| Medically Improved Outcomes | Medical |
| Million ( Swiss) | Messaging |
| Maritime Interdiction Operation | Military and Defence |
| Maritime Interception Operations | Military and Defence |
| Masked Input Output | Networking |
| MIAMI Municipal Airport, Miami, Oklahoma | Regional |
| Management Integration Office | Space Science |
