| M.C.T.D. | Mixed Connective Tissue Disease |
|---|---|
| M.D.D. | Major Depressive Disorder |
| M.D.I. | Metered Dose Inhaler |
| M.E.C. | minimal effective concentration |
| M.E.D. | Multiple epiphyseal dysplasia |
| M.E.M. | Minimum Essential Medium |
| m.e.p.c. | Miniature end-plate current |
| M.E.S. | Maximal Electroshock Seizure |
| M.f. | Micropolyspora faeni |
| M.F. | mitogenic factor |