| Acronym | Definition |
|---|
| MCO | Monaco (ISO Country code) |
| MCO | Managed Care Organization |
| MCO | Marine Corps Order |
| MCO | Mars Climate Orbiter |
| MCO | Medical College of Ohio (Toledo, OH, USA) |
| MCO | Manufacturer's Certificate of Origin |
| MCO | Major Combat Operations |
| MCO | Miscellaneous Charge Order (airline industry financial term) |
| MCO | Modern Chess Openings |
| MCO | Motor City Online (game) |
| MCO | Miscellaneous Charges Order |
| MCO | Master Control Operator |
| MCO | Multi-Canister Overpack |
| MCO | Military Claims Office |
| MCO | Movement Control Officer |
| MCO | Machinery Checkout |
| MCO | Maintenance Changeout |
| MCO | Orlando, FL, USA - Orlando International Airport (Airport Code) |
| MCO | Material Control Officer |
| MCO | Management Control Officer |
| MCo | Middle Cornish (linguistics) |
| MCO | Manufacturing Change Order |
| MCO | Mobile Cellular Operator |
| MCO | Manila Chamber Orchestra |
| MCO | Major Contingency Operation (US Army) |
| MCO | Minnesota Citizens Online |
| MCO | Missile Control Officer |
| MCO | Manual Changeover Signal (ITU-T) |
| MCO | Merchandise Coordinator |
| MCO | Melbourne Community Orchestra (Melbourne, FL) |
| MCO | Music Company Orchestra (Saratoga Springs, NY) |
| MCO | Metropolitan Chamber Orchestra (Columbus, OH) |
| MCO | Motor Sport Club of Ottawa |
| MCO | Maintenance Criticality Oriented |
| MCO | Military Corporation Office |
| MCO | Maneuver Control Officer |
| MCO | Motor Carrier Office |
| MCO | Meat Control Officers |
| MCO | Major Cultural Organization |
| MCO | Markov Chain Occupancy |
| MCO | Multi-Collaborative Overlay |
| MCO | Mobile Country Operator |
| MCO | Movements Control Office/Officer |
| MCO | Metropolitan Civic Orchestra (Charleston, SC) |