| Acronym | Definition |
|---|
| MSO | Manufacturers Statement of Origin |
| MSO | Microsoft Office |
| MSO | Microsoft Outlook |
| MSO | Multi System Operators |
| MSO | Mixed Signal Oscilloscope |
| MSO | Melbourne Symphony Orchestra |
| MSO | Milwaukee Symphony Orchestra (Milwaukee, WI) |
| MSO | Multiple System Operator |
| MSO | Medial Superior Olive |
| MSO | Mobile Switching Office |
| MSO | Multiple Service Operator |
| MSO | Mississippi Symphony Orchestra (Jackson, MS) |
| MSO | Mind Sports Olympiad |
| MSO | Monadic Second-Order Logic |
| MSO | L-Methionine Sulfoximine (amino acid) |
| MSO | Multicultural Student Organization |
| MSO | Military Service Obligation |
| MSO | Montreal Symphony Orchestra |
| MSO | Martha Stewart Omnimedia |
| MSO | Mexican Spotted Owl |
| MSO | Multisystem Operator (as in satellite/cable TV networks) |
| MSO | Medical Service Organization |
| MSO | Methylated Seed Oil |
| MSO | Military Support Officer |
| MSO | Mustard Seed Oil |
| MSO | Management Systems Office (various locations) |
| MSO | Most Serious Offense (criminal justice) |
| MSO | Management Services Officer |
| MSO | Member Service Organization (various organizations) |
| MSO | Malankara Syrian Orthodox (various locations) |
| MSO | multiple system operations |
| MSO | Minesweeper, Ocean (Non-Magnetic) |
| MSO | Multiple Spurious Operations (US NRC) |
| MSO | Mental State Assessment (various organizations) |
| MSO | Mees Solar Observatory (Maui, Hawaii) |
| MSO | Mind Sports Organisation (est. 1997; Canada) |
| MSO | Molten Salt Oxidation |
| MSO | Multi-Store Order |
| MSO | Map Support Office (US DoD) |
| MSO | Military Source Operation |
| MSO | Multi-Service Operational |
| MSO | Muslims Speak Out |
| MSO | Marine Safety Office(r) (US DoD) |
| MSO | Mixed Signal Option (Teradyne testers) |
| MSO | Mobilization Staff Officer (US DoD) |
| MSO | Migrant Student Organization (various organizations) |
| MSO | Mission Safety Officer |
| MSO | Moving Swiftly On |
| MSO | Marine Survey Office |
| MSO | Must Start On (project management) |
| MSO | Mutual Service Office (insurance) |
| MSO | Military Satellite Communications (MILSATCOM) Systems Organization (US DoD) |
| MSO | Maplewood/South Orange (New Jersey) |
| MSO | Master Security Officer |
| MSO | Missoula, MT, USA - Missoula International (Airport Code) |
| MSO | Major Service Outage |
| MSO | Medical Second Opinion |
| MSO | Midland Symphony Orchestra (Midland, Michigan) |
| MSO | Mid-Atlantic Symphony Orchestra (Ocean City, MD) |
| MSO | My Sweet One (Phish song) |
| MSO | Mariposa Symphony Orchestra (Mariposa, CA) |
| MSO | Molecular Spin Orbital |
| MSO | Methionine Sulfone (code for modified amino acid) |
| MSO | Morale Support Officer |
| MSO | Mckeesport Symphony Orchestra (McKeesport, PA) |
| MSO | Medical Stores Organisation |
| MSO | Manager of Search Operations |
| MSO | Mission Support Officer |
| MSO | Mobile Switch Office |
| MSO | Multimedia Service Operator |
| MSO | Mail Stream Optimization |
| MSO | Managed Services Organisation |
| MSO | Middlesex Sheriff's Office (Medford, MA) |
| MSO | Manufacturing Shop Order |
| MSO | Multiple Subscriber Organization |
| MSO | MILSATCOM Systems Office |
| MSO | Main Street Office |
| MSO | Marketing & Sales Office |
| MSO | Murray Symphony Orchestra (Murray, UT) |
| MSO | Maintenance Stores Office |
| MSO | Montessori School of Ojai (Ojai, CA) |
| MSO | Marketplace Services Organization (Canada) |
| MSO | Materiel Status Officer |
| MSO | macro saccadic oscillation |
| MSO | Maintenance Support Office |
| MSO | Minor Service Order |
| MSO | MSE Systems Overhaul |
| MSO | Maintenance Spare Optimization |
| MSO | Most/Main/More Significant Other (Polyamory) |
| MSO | Medical Support Order (health care) |
| MSO | Military Supply Officer |
| MSO | Military Satellite Officer |
| MSO | Mission Space Objects |
| MSO | Mission Staging Operation(s) |
| MSO | Methadone Support Organization |
| MSO | Major Sales Opportunities |
| MSO | Machine Superior to Operator |
| MSO | My Simple Office (Simple Office Solutions, Inc software) |
| MSO | Maritme Security Operations (US) |
| MSO | Major Sponsoring Organization |