master-at-arms

Short definition from Wiktionary

Noun

1. 1
   A warrant officer or chief petty officer responsible for discipline aboard a naval ship.
2. 2
   A commissioned officer responsible for overseeing all fitness training in subordinate units.
3. 3
   A petty officer responsible for law enforcement, antiterrorism, force protection, and expeditionary warfare.
4. 4
   An officer in a fraternal or similar organization charged with maintaining order.