(military) A soldier of private rank in cavalry or armour.

(military) A cavalry horse; a charger.

(military) A soldier.

(Britain, nautical, military) A troopship.

(US, law enforcement) Ellipsis of state trooper.

(Australia, law enforcement) A mounted policeman.

(figurative, colloquial) One who endures adversity or hardship with an attitude of stoicism and persistence.

To work as a trooper.

To work steadily at an unpleasant job without complaint.