| M | Male✓ Verified | Biology |
| M&S | Marks & Spencer✓ Verified | Company |
| MA&UD | Municipal Administration & Urban Development✓ Verified | Government, Civic Administration, Municipal Corporation, Department |
| MAC | Multi-Agency Centre✓ Verified | Agency, Intelligence Agency |
| MAIT | Manufacturers' Association for Information Technology✓ Verified | Association, Business, Forum, Industry, Manufacturing |
| MAIT | Multidisciplinary Accident Investigation Team✓ Verified | Accident, Group, Investigation, Safety, Team |
| MAL | MIPS Assembly Language✓ Verified | Computer Programming, Programming Language, Technology |
| MCA | Masters of Computer Applications✓ Verified | Education, Degree |
| MCD | Municipal Corporation of Delhi✓ Verified | Municipal Corporation |
| MCS | Maldives Customs Service✓ Verified | Agency, Government, Police, Law Enforcement |
| MDA | Magen David Adom✓ Verified | Disaster, Medical, Organization |
| MEDEVAC | Medical Evacuation✓ Verified | Military, Defence, Medical, Equipment, Transport |
| MESMA | Module d'Energie Sous-Marine Autonome✓ Verified | Technology, Transport, Water Transport, Submarine |
| MGBY | May God Bless You | Others |
| MK-404 | Vasilevo, North Macedonia✓ Verified | Others, Postal Code, Geography, Territory |
| MMRDA | Mumbai Metropolitan Region Development Authority✓ Verified | Agency, Government, Organization |
| MO | Medical Oddity✓ Verified | Medical, Disease |
| MOF | Middle of the Funnel (also known as MOFU)✓ Verified | Marketing, Sales |
| MOM | Mars Orbiter Mission✓ Verified | Science |
| MOM | Middle of Month✓ Verified | Time, Month, Slang |
| MOM | Minutes of Meeting✓ Verified | Business, Corporate, Email |
| MOM | Month over Month✓ Verified | Measurement Unit, Time, Month, Slang |
| MOM | Mother✓ Verified | Slang |
| MS | Microsoft Corporation✓ Verified | Company, Internet, Technology |
| MSA | Maritime Safety Administration✓ Verified | Agency, Government, Maritime, Safety, Water Transport |
| MSA | Master Services Agreement✓ Verified | Business, Legal |
| MSG | Master Sergeant✓ Verified | Military, Designation / Rank |
| MSgt | Master Sergeant✓ Verified | Military, Army, Marine Corps, Navy, Designation / Rank |