| Acronym | Definition |
|---|
| MO | Month |
| MO | Missouri (US postal abbreviation) |
| MO | Money Order |
| MO | Magneto-Optical |
| MO | Modus Operandi (Latin: mode of operating) |
| MO | Montana (less common) |
| Mo | Mouse (medical research specimen) |
| MO | Morocco (Including Ifni) |
| MO | Macau (ISO country code, top level domain) |
| MO | Mobile Office |
| MO | Mobile Office (Airtel) |
| MO | Mail Order |
| Mo | Morse (nautical) |
| MO | Modena (Emilia Romagna, Italy) |
| MO | Molybdenum |
| MO | Philip Morris (stock symbol) |
| MO | Altria Group, Inc. (stock symbol) |
| MO | Medical Officer |
| MO | Microwave Oven |
| MO | MU Online (gaming) |
| MO | Main Objective |
| MO | Motor Oil |
| MO | Mode Of Operation |
| MO | Mineral Oil |
| MO | Metal Oxide |
| MO | Management Operations |
| MO | Mostar (auto registration for Mostar, Bosnia) |
| MO | Marketing Optimization |
| MO | Moral Obligation |
| MO | Molecular Orbital |
| MO | Member Organization |
| MO | Microorganism |
| MO | Marching Orders |
| MO | Morbidly Obese |
| MO | Mahavishnu Orchestra (jazz-rock fusion group) |
| MO | Magnum Opus |
| MO | Mobile Operator |
| MO | Mobile Originated (telecommunications) |
| MO | Mobile Station |
| MO | Method of Operation |
| MO | Marine Officer |
| MO | Michael Olowokandi (basketball player) |
| MO | Managed Object |
| MO | Middle Office |
| MO | Mixed Oxide |
| MO | Mortal Online (gaming) |
| MO | Modern Orthodox |
| MO | Metal Object |
| MO | Management Object (OSI) |
| MO | Manual Override |
| MO | Metalorganic |
| MO | Maintenance Officer |
| MO | Mega Octet (French: megabyte) |
| MO | Mars Observer |
| MO | Military Outpost (gaming, Pardus) |
| MO | Modification Order |
| MO | Mathematical Olympiad |
| MO | Master Oscillator |
| MO | Manpower Office |
| MO | Masonry Opening |
| MO | Manufacturing Order |
| MO | Movement Orders |
| MO | Maintenance Optimization (mathematical model) |
| MO | MapObject |
| MO | Medical Orderly |
| MO | Milicja Obywatelska (former Polish police) |
| MO | Mission Orders |
| MO | Madonion.com |
| MO | Medula Oblongata |
| MO | Morpholino antisense Oligonucleotide |
| MO | Manpower and Organization |
| MO | Mission Observer |
| MO | Management Systems Office (NIMA) |
| MO | Maps and Overlays |
| MO | McLean Orchestra (McLean, VA) |
| MO | Miscellaneous Operation |
| MO | Mesio-Occlusal (dentistry) |
| MO | Mostly Orthogonal |
| MO | Microbe Obliterator (WALL-E) |
| MO | MOD51 (assembly language ASM51 assembler control) |
| MO | Massey-Omura (multiplier) |
| MO | Myst Obsession (gaming website) |
| MO | Munitions Operations |
| MO | Musa-Okumoto (logarithmic Poisson method) |
| MO | Manomet Observatory (University of Missouri, Columbia, Biological Sciences, Columbia, MO) |
| MO | Magnesia Oil (Haley's) |
| MO | Module Outfitting |
| MO | Militia Operative |
| MO | Medium Offense (gaming) |
| MO | Maintenance & Operations/Operating |