Emily Dickinson Lexicon

DRA-GOON', n. [Fr. dragon; Sp. id.; Port. dragam, a dragon and dragoon; It. dragone; G. dragoner; D. dragoner; Dan. dragon; Sw. id.; L. draconarius, an ensign bearer, from draco, dragon; an appellation given to horsemen, perhaps for their rapidity or fierceness.]

A soldier or musketeer who serves on horseback or on foot, as occasion may require. Their arms are a sword, a musket and a bayonet. – Encyc.