pillion

noun

1. a pad or cushion attached behind a saddle, especially as a seat for a woman.
2. a pad, cushion, saddle, or the like, used as a passenger seat on a bicycle, motor scooter, etc.
3. a passenger’s saddle or seat behind the driver’s seat on a motorcycle.

noun

1. a seat or place behind the rider of a motorcycle, scooter, horse, etc

adverb

2. on a pillionto ride pillion

n.kind of saddle, c.1500, of Celtic origin (cf. Irish pillin, Gaelic pillin), ultimately from Latin pellis “skin, pelt” (see film (n.)).