Webster's Revised Unabridged Dictionary · 1913

Trooper

Trooper , noun

1.
A soldier in a body of cavalry; a cavalryman; also, the horse of a cavalryman.
2.
A state police officer; -- also called state trooper. [United States]

The black troopers of Queensland are a regiment of aboriginal police, employed chiefly for dispersing wild aborigines who encroach on sheep runs.

3.
A mounted policeman. [Australia]
4.
Trouper.
Collocations (1)
like a trooper , with energy, endurance, or enthusiasm; as, to work like a trooper.