HMP
Initialism of Her/His Majesty's Penitentiary.
Proper noun
- Initialism of Her/His Majesty's Penitentiary.
- Abbreviation of Her/His Majesty's Prison The name of several prisons in the British Commonwealth and British Empire.
Noun
- Initialism of Her/His Majesty's Prison: The prefix used in the names of prisons in the United Kingdom.
- Abbreviation of hazard mitigation plan.