bluecoat

noun

1. (British, attributive, often)A pupil attending any of certain prestigious British schools having a traditional dress code.

   “This was a bluecoat school in my day.”

2. (US)A soldier or officer in the Union army during the American Civil War.

   “The shot wounded Thomas Lord, a 73-year-old former New York City police officer from Suffolk, Va., and a bluecoat with the Seventh New York Volunteer Cavalry.”

3. (dated)A policeman.

   “Holonym: thin blue line”

   “"The offices are up those steps," said the bluecoat.”