| Word | Description |
| MADT | Monthly Average Daily Traffic |
| MarMac | Marmac Tape |
| MicroTally | MicroTally |
| Motion Loop Dectector (Directional) | An induction loop detector consisting of two separate loops either closely spaced or partially overlapping which is not affected by the passage of a vehicle except in the desired direction. |
| Motion Loop Detector (Nondirectional) | An induction loop detector which is capable of being actuated by the passage of a vehicle over any portion of the loop. |
| MPO | Metropolitan Planning Organization |