dragoon (n.)
1620s, from French dragon "carbine, musket," because the guns the soldiers carried "breathed fire" like a dragon (see dragon). Also see -oon.
dragoon (v.)
1680s, literally "to force by the agency of dragoons" (which were used by the French kings to persecute Protestants), from dragoon (n.). Related: Dragooned; dragooning.