M in WordNet English dictionary

1. the cardinal number that is the product of 10 and 100
   thousand  one thousand  1000  M  K  chiliad  G  grand  thou  yard 
   
2. concentration measured by the number of moles of solute per liter of solution
   molarity  molar concentration  M 
   
3. the 13th letter of the Roman alphabet
   M  m 
   
4. a unit of information equal to 1024 kibibytes or 2^20 (1,048,576) bytes
   megabyte  mebibyte  M  MB  MiB 
   
5. a unit of information equal to 1000 kilobytes or 10^6 (1,000,000) bytes
   megabyte  M  MB 
   
6. the 13th letter of the Roman alphabet
   M  m