'Coursers' in the Bible

And the barley, and the straw for the horses and coursers, they brought to the place where the superintendents were, every man according to his charge.

And he wrote in the name of king Ahasuerus, and sealed it with the king's ring, and sent letters by couriers on horseback riding on coursers, horses of blood reared in the breeding studs:

The couriers mounted on coursers and horses of blood went out, being hastened and pressed on by the king's commandment. And the decree was given at Shushan the fortress.