| Abbreviation | Definition |
|---|---|
| MRIP | Monu River Irrigation Project |
| MRIP | Municipal Recycling Incentive Program |
| MRN | Maryland Recycling Network |
| MRPI | Milieu Relevante Product Informatie |
| MRR | Materials Recovery And Recycling |
| MRRF | Material Recovery Recycling Facility |
| MRRF | mitochondrial ribosome recycling factor |
| MRRP | Monofilament Recovery and Recycling Program |
| MRRP | Monofilament Recovery Recycling Program |
| MRRP | Monofilament Recycling Recovery Program |
| MRW | Mad River Watch |
| MRW | Materials Recycling World |
| MRW | Molalla River Watch |
| MRWA | Merseyside Recycling and Waste Authority |
| MRWPCA | Monterey Regional Water Pollution Control Agency |
| MRWS | Managing Radioactive Waste Safely (UK) |
| MSBD | Minor Source Baseline Date |
| MSCE | Master of Science in Civil and Environmental |
| MSCP | Multiple Species Conservation Program |
| MSDS | Minimum Safety Data Score |