| M1 | mitral first [sound]; myeloblast; slight dullness |
|---|---|
| 3-M [syndrome] | initials for Miller, McKusick, and Malvaux, who first described the syndrome |
| MI | first meiotic metaphase; maturation index; medical illustrator; medical informatics; medical inspect... |
| MS | I, II, III, IV medical student-first, second, third, and fourth year |
| NI-NXII | first to twelfth cranial nerves |