名詞 pillion:

1. a seat behind the rider of a horse or motorbike etc.

pil.lion

n.（名詞）
A pad or cushion for an extra rider behind the saddle on a horse or motorcycle.
座墊，后座：在馬鞍或摩托車座位后給另一乘坐者準備的墊子或鞍墊
A bicycle or motorcycle saddle.
車座：自行車或摩托車坐墊

來源：
Probably from Scottish Gaelic pillean [diminutive of] peall [rug]
可能源自 蘇格蘭的蓋爾語 pillean [] peall的小后綴 [小地毯]
or Irish Gaelic pillín [diminutive of] pell [rug]
或 愛爾蘭蓋爾語 pillín [] pell的小后綴 [小地毯]
both from Old Irish pell
都源自 古愛爾蘭語 pell
from Latin pellis [animal skin] * see pel- 3
源自 拉丁語 pellis [動物皮] *參見 pel- 3