Sumpter /(?)/

Sump·ter

Sumpter

n.
  1. The driver of a pack horse. [Obs.]
  2. A pack; a burden. [Obs.]
  3. An animal, especially a horse, that carries packs or burdens; a baggage horse.

Sumpter

a.
  1. Carrying pack or burdens on the back; as, a sumpter horse; a sumpter mule.