Emily Dickinson Lexicon

PIL-LION, n. [pil'yun; Ir. pillin; from pile, L. pilus, hair, or from stuffing. See Pillow.]

1. A cushion for a woman to ride on behind a person on horseback. – Swift.
2. A pad; a pannel; a low saddle. – Spenser.
3. The pad of a saddle that rests on the horse's back.