| moribund | At the point of dying; in terminal decline—lacking vitality or vigor | |
| mores | The essential or characteristic customs and conventions of a community | |
| mordant | Having or showing a sharp or critical quality; biting | |
| morbid | Characterized by an abnormal and unhealthy interest in disturbing and unpleasant subjects, especially death and disease | |
| morass | An area of muddy or boggy ground | |
| monastic | Relating to monks, nuns, or others living under religious vows, or the buildings in which they live | |
| mitigate | To make less severe, serious, or painful | |
| misnomer | A wrong or inaccurate use of a name or term | |
| miserly | Of, relating to, or characteristic of a miser; very stingy or frugal. | |
| minion | A follower or underling of a powerful person, especially a servile or unimportant one | |