According to Wikipedia MP stands for.......

• Mending plate
• Military police
• Mumbai Police
• Machine pistol
• Manu propria, Latin for with one's own hand
• Martinair IATA airline designator or reservation code
• Making a Packet in expense claims
  
• Member of Parliament
• Metropolitan Police or Municipal police
• mezzo-piano, a musical term meaning "medium-quiet" or "moderately-quiet"
• Miljöpartiet, Swedish green party
• Missouri Pacific Railroad reporting mark
• Modus ponens, Latin for mode that affirms
• Mooring Post
• Mp (digraph)
• Ministério Público
• Medida provisória
• Missionary position

Wikipedia - MP