| Acronym | Definition |
|---|
| OM | Onder Meer (Dutch: among others) |
| OM | Old Man (Amateur Radio) |
| OM | Oh My |
| OM | Oriental Medicine |
| OM | Oman (ISO country Code, top level domain) |
| OM | On the Move |
| OM | Olympique de Marseille (French football team) |
| OM | Organic Matter |
| OM | Office Manager |
| OM | Openbaar Ministerie |
| OM | Oh Man |
| OM | Order Management |
| OM | Olivia Munn (actress) |
| OM | Osteomyelitis (bone infection) |
| OM | Old Mutual (London, UK financial services) |
| OM | Offering Memorandum (investing) |
| OM | Omeprazole (drug) |
| OM | Object Model |
| OM | Orgasmic Meditation |
| OM | Order of Merit |
| OM | Operations and Maintenance |
| OM | Operating Manual |
| OM | Odyssey of the Mind |
| OM | Officemax (retail business) |
| OM | Otitis Media |
| OM | Orbit Micro |
| OM | Occupational Medicine (also seen as OCCMED and OCC MED) |
| OM | Oscar Mayer |
| OM | Ordained Minister |
| OM | Operation Mobilisation (global Christian missionary organisation) |
| OM | Optical Microscopy |
| OM | Operating Margin (gross margin less operating expenses) |
| OM | Oliebranchens Miljøpulje (Denmark) |
| OM | Mongolian Airlines (IATA airline code) |
| OM | Outer Marker |
| OM | Open Marriage (lifestyle) |
| OM | Operational Manager |
| OM | Orden Ministerial (Spanish) |
| OM | Obtuse Marginal |
| OM | Operational Modeling |
| OM | OpenMail |
| OM | Operation Migration |
| OM | Optical Model |
| OM | Operating Methods |
| OM | Organizational Maintenance |
| OM | Ontology Matching |
| OM | Operator Maintenance |
| OM | Optical Monitor (astrophysics, astronomy) |
| OM | Optical Module (Ciena) |
| OM | Organizational Membership |
| OM | Organo Metallic |
| OM | Operations Module |
| OM | Organized Militia |
| OM | Office of Meteorology |
| OM | Optics Module |
| OM | Orbital Module |
| OM | Opticalman (US Navy rating) |
| OM | Optical Multiplexer (Sprint) |
| OM | OPTera Metro (Cisco) |
| OM | O-Methylation |
| OM | Operational Measurement |
| OM | Overlay Manager |
| OM | Optimization of Middleware |
| OM | Operations Manager/Management |
| OM | Open Marketing |
| OM | Optionsmäklarna (Swedish company; now OM Gruppen) |
| OM | Out for Maintenance |
| OM | Omni Mane (Latin: Every Morning) |
| OM | OnMarketer |
| OM | Occipitalis Muscle |
| OM | Old Marlburian (Old Marlburian Lodge) |
| OM | Out of Band Modulator |
| OM | Office Macro Virus |
| OM | Outsource Marketing, LLC |
| OM | Off-Line Memory (DSC) |
| OM | Old Malvernian (England, UK) |
| OM | Operational Manning |
| OM | Overlapping Multicarrier |
| OM | Obtuse Mule |
| OM | Orbiting Mirror |
| OM | Minim Fathers (religious order) |
| OM | Operator's/Operation Manual |
| OM | Occultation Measurement |
| OM | Old McFarlane |
| OM | (USN Rating) Opticalman |
| OM | Ostial Membrane |