| Acronym | Definition |
|---|
| MAR | March |
| Mar | Marshal |
| MAR | Mars (French: March) |
| MAR | Morocco (ISO Country code) |
| MAR | Mid-Atlantic Ridge |
| MAR | Mardi (French: Tuesday) |
| Mar | Marshal (International Order of DeMolay) |
| MAR | Medication Administration Record |
| MAR | Massachusetts Association of Realtors |
| MAR | Martius (Latin: March) |
| MAR | Maintenance & Repair |
| MAR | Marcato |
| MAR | Minorities at Risk (research project; University of Maryland) |
| MAR | Missing At Random |
| MAR | Marfa, Texas (border patrol sector) |
| MAR | Multiple Antibiotic Resistance |
| MAR | Memory Address Register |
| MAR | Mean Annual Runoff |
| MAR | Monthly Activity Report |
| MAR | Master of Arts in Religion |
| MAR | Mahmoud Abdul-Rauf (basketball player) |
| MAR | Mobile Access Router (Cisco) |
| MAR | Minnesota Association of Realtors (chartered 1947) |
| MAR | Major Account Representative |
| MAR | Mercury Arc Rectifier (electronics) |
| MAR | Material At Risk |
| MAR | Mississippi-Atchafalaya River |
| MAR | Mobile Autonomous Robot |
| MAR | Maracaibo, Venezuela - La Chinita (Airport Code) |
| MAR | Microprogram Address Register |
| MAR | Matrix Attached Region (molecular biology) |
| MAR | Major Area of Responsibility |
| MAR | Mutual Aid Region |
| MAR | Minimally Attended Radar |
| MAR | Military Aircraft Release |
| MAR | Mid-Appalachian Region |
| MAR | Mid-Air Retrieval |
| MAR | Medication Administration Report |
| MAR | Multifunction Array Radar |
| MAR | Micro Assault Rifle |
| MAR | Multiple Access Return |
| MAR | Multiple-Access Return |
| MAR | Management and Administration Regulations (UK) |
| MAR | Military Aviation Review (UK) |
| MAR | Mission Analysis Room |
| MAR | Major Aircraft Review |
| MAR | Mission Analysis Report |
| mAR | Mouse Androgen Receptor |
| MAR | Method of Analytical Regularization |
| MAR | Major Assembly Release |
| MAR | Moist Adiabatic Rate (meteorology) |
| MAR | Middle American Radical |
| MAR | Maximum Allowable Residue |
| MAR | Management Attainment Report |
| MAR | Mid-Atlantic Review |
| MAR | Major Acquisition Review (FAA) |
| MAR | Monthly Acquisition Report |
| MAR | Main Avionics Rack |
| MAR | Middeck Accommodations Rack (Space Shuttle) |
| MAR | Maintenance Action Request |
| MAR | Macrocytic Anemia, Refractory, due to 5q deletion |
| MAR | METOC assistance request (US DoD) |
| MAR | Mobius Area Representative |
| MAR | Multi-Alternate Route |
| MAR | Maintenance Assistance Request |
| MAR | Mass to Air Ratio |
| MAR | Mission Area Review |
| MAR | Management Assessment Report/Review |
| MAR | Multi-Scale Auto-Regressive |
| MAR | Multi-Aromatic Resin (electronics) |
| MAR | Maintenance Analysis Referral |
| MAR | Mitigated Auxiliary Receiver |
| MAR | Multimedia Authorization Request |
| MAR | Material Approval Request |
| MAR | Museum of the American Railroad (Texas; est. 1962) |