| Abbreviation | Definition |
|---|---|
| CMLZ | Containers Marine Lines Isbrandtsen |
| CMMU | Medcontainers |
| CMO | Chicago, St. Paul, Minneapolis and Omaha Railway (Union Pacific Railroad) |
| CMO | Union Pacific Railroad Company |
| CMPA | City of Madison Port Authority |
| CMPA | Madison Railroad Division of City of Madison Port Authority |
| CMPH | Camp Trucking Company, Inc. |
| CMPU | Complete Logistics |
| CMPU | Complete Logistics Company |
| CMQ | Central Maine and Quebec Railway |
| CMR | Central Midland Railway |
| CMRI | Computer/Model Railroad Interface |
| CMRL | Chennai Metro Rail Limited |
| CMRL | Chennai Metro Rail Ltd |
| CMSN | Crowley Marine Services |
| CMSU | Crowley Marine Services |
| CMU | Columbus Charter Service |
| CMUU | Canada Maritime Agencies Limited |
| CMX | Control Meta X |
| CN | Canadian National |