MB in WordNet English dictionary

1. (a British degree) a bachelor's degree in medicine
   Bachelor of Medicine  MB 
   
2. a unit of information equal to 1024 kibibytes or 2^20 (1,048,576) bytes
   megabyte  mebibyte  M  MB  MiB 
   
3. a unit of information equal to 1000 kilobytes or 10^6 (1,000,000) bytes
   megabyte  M  MB