What is the meaning of Trooper?

A soldier of private rank in cavalry or armor.

A cavalry horse; a charger.

A soldier.

A troopship.

Ellipsis of state trooper.

A mounted policeman.

Misspelling of trouper (one who stoically endures adversity).

To work as a trooper.

To work steadily at an unpleasant job without complaint.

Source: wiktionary.org