| Prefix with marine | 18 |
| Prefix with market | 18 |
| Prefix with marketer | 20 |
| Prefix with marketing | 21 |
| Prefix with marketing or commuting | 34 |
| Prefix with marketing or vision | 31 |
| Prefix with marry and mingle | 28 |
| Prefix with mart or skirt | 25 |
| Prefix with Marxism or Darwinism | 32 |
| Prefix with masochism | 21 |
| Prefix with match or fire | 25 |
| Prefix with mate or graph | 25 |
| Prefix with matter | 18 |
| Prefix with mature | 18 |
| Prefix with mechanics | 21 |
| Prefix with media | 17 |
| Prefix with medic | 17 |
| Prefix with meditated | 21 |
| Prefix with mensch | 18 |
| Prefix with mentioned | 21 |
| Prefix with merge | 17 |
| Prefix with meter | 17 |
| Prefix with meter and liter | 27 |
| Prefix with meter and printer | 29 |
| Prefix with meter and scope | 27 |
| Prefix with meter or bel | 24 |
| Prefix with meter or gram | 25 |
| Prefix with meter or liter | 26 |
| Prefix with meter or methylene | 30 |
| Prefix with meter or motor | 26 |
| Prefix with meter or phrase | 27 |
| Prefix with meter or scope | 26 |
| Prefix with meter or sphere | 27 |
| Prefix with meter or trooper | 28 |
| Prefix with meter or tude | 25 |
| Prefix with meter or vise | 25 |
| Prefix with metric | 18 |
| Prefix with metric or tonic | 27 |
| Prefix with metrics | 19 |
| Prefix with metrics or bar | 26 |
| Prefix with millionaire | 23 |
| Prefix with millions | 20 |
| Prefix with mime or graph | 25 |
| Prefix with mingle or mix | 25 |
| Prefix with mission or press | 28 |
| Prefix with mix | 15 |
| Prefix with mobile | 18 |
| Prefix with modern | 18 |
| Prefix with modulator | 21 |
| Prefix with molecular | 21 |
| Prefix with mom | 15 |
| Prefix with mom, coined after historic 2009 births | 50 |
| Prefix with monde | 17 |
| Prefix with moron | 17 |
| Prefix with morph | 17 |
| Prefix with morphic | 19 |
| Prefix with morphosis | 21 |
| Prefix with mother and brother | 30 |
| Prefix with mount | 17 |
| Prefix with mural | 17 |
| Prefix with mural or galactic | 29 |
| Prefix with mural or muscular | 29 |
| Prefix with mural or party | 26 |
| Prefix with mural or state | 26 |
| Prefix with mural or venous | 27 |
| Prefix with muscular and transmitter | 36 |
| Prefix with musicology | 22 |
| Prefix with mutuel | 18 |
| Prefix with name or charge | 26 |
| Prefix with name or face | 24 |
| Prefix with nasal or facial | 27 |
| Prefix with nasal that means 'mouth' | 44 |
| Prefix with natal | 17 |
| Prefix with natal or classical | 30 |
| Prefix with natal or noir | 25 |
| Prefix with natal or nuptial | 28 |
| Prefix with natal or plastic | 28 |
| Prefix with national | 20 |
| Prefix with national or grain | 29 |
| Prefix with naut or sol | 23 |
| Prefix with nautical | 20 |
| Prefix with night and day | 25 |
| Prefix with night or day | 24 |
| Prefix with night or light | 26 |
| Prefix with nitrile | 19 |
| Prefix with noir | 16 |
| Prefix with normal | 18 |
| Prefix with nuclear or freeze | 29 |
| Prefix with nuclear or plastic | 30 |
| Prefix with nucleotide | 22 |
| Prefix with nuke or freeze | 26 |
| Prefix with nuptial | 19 |
| Prefix with ode or pod | 22 |
| Prefix with ophthalmology | 25 |
| Prefix with orthodox | 20 |
| Prefix with owned or occupied | 29 |
| Prefix with oxide | 17 |
| Prefix with pad | 15 |
| Prefix with pad or port | 23 |
| Prefix with pad or taxi | 23 |