blue shirt

Short definition from Wiktionary

Noun

1. 1
   An Alaska State Trooper.
2. 2
   A sailor who works on the flight deck of an aircraft carrier, securing aircraft to the deck.
3. 3
   An emergency medical service worker; a paramedic.
4. 4
   Used other than figuratively or idiomatically: see blue, shirt.
5. 5
   Alternative form of blue shirt.