A courser is a swift and strong horse, frequently used during the Middle Ages as a warhorse. It was ridden by knights and men-at-arms.
Coursers are commonly believed to be named for their running gait, (from Old French cours, 'to run'). However, the word possibly derived from the Italian corsiero, meaning 'battle horse'.
The courser was more common than the destrier, and used for battle as they were light, fast and strong. They were valuable horses, but less expensive than the highly prized destrier. Another horse commonly ridden during war was the rouncey, an all-purpose horse.
Coursers were also used occasionally for hunting.