| MDTR | mean diameter-thickness ratio |
|---|---|
| MED | median erythrocyte diameter; medical, medication, medicine; Medical Entities Dictionary; minimum eff... |
| MMAD | mass median aerodynamic diameter |
| MMD | mass median diameter; minimum morbidostatic dose; moyamoya disease; myotonic muscular dystrophy |
| OD | Doctor of Optometry; obtained absorbance; occipital dysplasia; occupational dermatitis; occupational... |