Sumpter

1. a. Carrying pack or burdens on the back; as, a sumpter horse; a sumpter mule.
2. n. The driver of a pack horse.
3. n. A pack; a burden.
4. n. An animal, especially a horse, that carries packs or burdens; a baggage horse.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.