| Term | Definition |
| monarchy | rule by a single person |
| monochromatic | of one color |
| monocle | eyeglass for one eye |
| monogamy | marriage with one mate at a time |
| monogram | two or more letters interwoven to represent a name |
| monograph | written account of a single thing or class of things |
| monolith | single stone of large size; obelisk |
| monolithic | massive and rigdly uniform |
| monolog(ue) | long speech by one person |
| monomania | excessive concentration on one idea or subject |
| monomorphic | having a single form |
| monosyllabic | having one syllable |
| monotheism | belief that there is one God |
| monotonous | continuing in an unchanging tone; wearing |