| M&O | Maintenance and Operation 
| Others |
| M&O | Maintenance and Operations
| Others |
| M&O | Maps and Overlays (Client)
| Others |
| M.O. | modus operandi [Lat. equiv. method of operating]
| Others |
| M.O. | modus operandi [Lat. method of operation]
| Others |
| MO | Macau
| Others |
| MO | Machine Object
| Others |
| MO | Magic Orlando
| Others |
| MO | Magneto-Optic
| Others |
| MO | Magneto-Optical
| Others |
| MO | Mail Order
| Others |
| MO | Main Objective
| Others |
| MO | Main Organizer
| Others |
| MO | Maintenance Operations
| Others |
| MO | Maintenance Operator
| Others |
| MO | Major Objective
| Others |
| MO | Majority Opinion
| Others |
| MO | Male Only
| Others |
| MO | Managed Object
| Others |
| MO | Management Office
| Others |
| MO | Mandibular Organ
| Others |
| MO | Manned Orbiter
| Others |
| MO | Manual Orientation
| Others |
| MO | Manufacturing Order
| Others |
| MO | Marco
| Others |
| MO | Marketing Officer
| Others |
| MO | Mars Observer
| Others |
| MO | Masonry Opening
| Others |
| MO | Master of Obsolescence
| Others |
| MO | Master of Obstetrics
| Others |
| MO | Master of Osteopathy
| Others |
| MO | Master Oscillator
| Others |
| MO | Mastery Operations
| Others |
| MO | Math Oltmpiads
| Others |
| MO | Mathematical Operation
| Others |
| MO | Maximum Overdrive
| Others |
| MO | May Overby Elementary School
| Others |
| MO | Medical Oddity
| Others |
| MO | Medical Office
| Others |
| MO | Medical Officer
| Others |
| MO | Medical Officers
| Others |
| MO | Medical Oxygen
| Others |
| MO | Medulla Oblongata
| Others |
| MO | Mega-Octet (Megabyte)
| Others |
| MO | Membrane Oxygenator
| Others |
| MO | Mercedes Only
| Others |
| MO | Mercedes Original
| Others |
| MO | Mesial Occlusal
| Others |
| MO | Meta Object
| Others |
| MO | Metal Oxide
| Others |
| MO | Metal-Organic
| Others |
| MO | Meteorological Office
| Others |
| MO | Meter Outlet
| Others |
| MO | Method of Operation
| Others |
| MO | Methyl Orange
| Others |
| MO | Micheal Obaras
| Others |
| MO | Michiel Overeem
| Others |
| MO | Micro-Organism
| Others |
| MO | Microbe Obliterator
| Others |
| MO | Mid-deck Overhead
| Others |
| MO | Middle Office
| Others |
| MO | Mildly Overrated
| Others |
| MO | Minsener Oog
| Others |
| MO | Mission Operations
| Others |
| MO | Mission Oriented
| Others |
| MO | Missouri
| State |
| MO | Missouri Oy
| Others |
| MO | Mitral Opening
| Others |
| MO | Mixed Object
| Others |
| MO | Mobile Field Office
| Others |
| MO | Mobile Originated
| Others |
| MO | Mobile Originating
| Others |
| MO | Mobility Order
| Others |
| MO | Mod Organizer
| Others |
| Mo | Mode
| Others |
| MO | Modena (Provence)
| Others |
| MO | Modifier Oxide
| Others |
| MO | Modula-3 Object file
| Others |
| MO | Modus Operandi
| Others |
| MO | Mohammad On
| Others |
| MO | Moldavian
| Others |
| mo | Moldovan
| Others |
| MO | Molecular Orbital
| Others |
| MO | Molecular Oriented
| Others |
| MO | Molybdenum
| Element |
| MO | MOment
| Others |
| MO | Momentum On
| Others |
| MO | Money order
| Others |
| MO | Mono-Oxygenase
| Others |
| MO | MOnoclonal
| Others |
| MO | MOnocyte
| Others |
| MO | Monotonic Convention
| Others |
| MO | MOntag
| Others |
| MO | Montana Or
| Others |
| mo | Month
| Others |
| MO | Morbid Obesity
| Others |
| MO | Morbidly Obese
| Others |
| MO | morphine
| Others |
| MO | Mostly Octet
| Others |
| MO | Mountain Oyster
| Others |
| MO | Mouth Opening
| Others |
| MO | Mouthwatering Options
| Others |
| MO | Movimiento Obrera
| Others |
| MO | Moving On
| Others |
| MO | Multi Objective
| Others |
| MO | Multiplayer Online
| Others |
| MO | Multiple Observations
| Others |
| MO | Multiple Osteochondromas
| Others |
| MO | Mustard Oil
| Others |
| MO | My Opinion
| Others |
| MO | Myositis Ossificans
| Others |
| MO | Philip Morris Companies Inc.
| Others |