What does "sumpter" mean?

Sumpter: A pack; a burden. [Obs.] Beau. & Fl.

Additional senses

  1. 2.An animal, especially a horse, that carries packs or burdens; a baggage horse. Holinshed.
  2. 3.Carrying pack or burdens on the back; as, a sumpter horse; a sumpter mule. Bacon.

Sources