| A | B |
| monochrome | having one color |
| monocle | an eyeglass for one eye |
| monolingual | speaking or writing only one language |
| monolith | something made out of one single large block or piece of stone; one single stone monument |
| monologue | a long speech given by one person |
| monophobia | the fear of being alone |
| monopoly | control of a product or service by one company |
| monorail | a track for subway or train cars that only has one rail |
| monosyllabic | a word that has only one syllable |
| monotone | a speech in which every word has one tone of voice |
| monotony | the same one thing over and over again that leads to boredom |
| mono | one |
| opposite of mono- | poly |