| Majority rule |
| Malowan six clubs convention |
| Marked finesse |
| Marx two clubs |
| Master card |
| Master hand |
| Mathe |
| Mathe asking bid |
| Maximal overcall double |
| McKenney signal |
| Mexican two diamonds |
| Michaels cuebid |
| Miles convention |
| Miles responses to two notump openings |
| Milton work count |
| Mini Notrump |
| Mini-Splinter |
| Minor suit Stayman |
| Minor suit Swiss |
| Minor suit Texas |
| Minor tenace |
| Mixed raise |
| Mosher |
| Moysian fit |
| Murray convention |
