| Prefix for modern | 17 |
| Prefix for mode or king | 23 |
| Prefix for mobile or pilot | 26 |
| Prefix for mix or fix | 21 |
| Prefix for mission | 18 |
| Prefix for millions | 19 |
| Prefix for metrical | 19 |
| Prefix for metric or tonic | 26 |
| Prefix for metric and tope | 26 |
| Prefix for metric | 17 |
| Prefix for meter or winkle | 26 |
| Prefix for meter or tude | 24 |
| Prefix for meter or tribe | 25 |
| Prefix for meter or spore | 25 |
| Prefix for meter or scope | 25 |
| Prefix for meter or pede | 24 |
| Prefix for meter or liter | 25 |
| Prefix for meter or gram | 24 |
| Prefix for meter | 16 |
| Prefix for mentioned | 20 |
| Prefix for medic or psychology | 30 |
| Prefix for medic or graph | 25 |
| Prefix for medic | 16 |
| Prefix for mature or dominant | 29 |
| Prefix for matter | 17 |
| Prefix for mate or mobile | 25 |
| Prefix for marketing | 20 |
| Prefix for many cold-weather product names | 42 |
| Prefix for many | 15 |
| Prefix for maniac | 17 |
| Prefix for mancy | 16 |
| Prefix for macassar | 19 |
| Prefix for logy or nomy | 23 |
| Prefix for logy and nomics | 26 |
| Prefix for logical or motor | 27 |
| Prefix for logical or gram | 26 |
| Prefix for logical | 18 |
| Prefix for logic or centric | 27 |
| Prefix for log or gram | 22 |
| Prefix for lock or view | 23 |
| Prefix for lock | 15 |
| Prefix for lithic or plastic | 28 |
| Prefix for lithic | 17 |
| Prefix for lingual | 18 |
| Prefix for linear | 17 |
| Prefix for light or night | 25 |
| Prefix for light | 16 |
| Prefix for life or wife | 23 |
| Prefix for liberal or conservative | 34 |
| Prefix for legal or sailing | 27 |
| Prefix for legal or normal | 26 |
| Prefix for legal or medic | 25 |
| Prefix for legal or chute | 25 |
| Prefix for legal | 16 |
| Prefix for lay or play | 22 |
| Prefix for lateral or librium | 29 |
| Prefix for lateral or distant | 29 |
| Prefix for lateral | 18 |
| Prefix for john or god | 22 |
| Prefix for inflammatory | 23 |
| Prefix for Impressionism | 24 |
| Prefix for iliac | 16 |
| Prefix for hood or handle | 25 |
| Prefix for hit or dose | 22 |
| Prefix for hero or knock | 24 |
| Prefix for hero | 15 |
| Prefix for head or lap | 22 |
| Prefix for hazard | 17 |
| Prefix for hap or deed | 22 |
| Prefix for gravure | 18 |
| Prefix for graphy | 17 |
| Prefix for graphic | 18 |
| Prefix for graph or vision | 26 |
| Prefix for graph or type | 24 |
| Prefix for graph or trooper | 27 |
| Prefix for graph or resin | 25 |
| Prefix for graph or medic | 25 |
| Prefix for graph or logical | 27 |
| Prefix for graph or harp | 24 |
| Prefix for graph | 16 |
| Prefix for gram or vision | 25 |
| Prefix for gram or tone | 23 |
| Prefix for gram or pest | 23 |
| Prefix for gram or nautical | 27 |
| Prefix for gram or naut | 23 |
| Prefix for gram or meter | 24 |
| Prefix for gram or lytic | 24 |
| Prefix for gram or logue | 24 |
| Prefix for gram or logical | 26 |
| Prefix for gram or glotis | 25 |
| Prefix for gram or dyne | 23 |
| Prefix for gram or drome | 24 |
| Prefix for gram and phone | 25 |
| Prefix for gram and cure | 24 |
| Prefix for gram and bar | 23 |
| Prefix for gram | 15 |
| Prefix for graduate or handed | 29 |
| Prefix for grade or active | 26 |
| Prefix for grade | 16 |
| Prefix for gothic or classic | 28 |