pillion: [16] The word pillion long predates the invention of the motorcycle. It originally denoted a ‘small light saddle on a horse’, particularly one placed behind a main saddle. It is ultimately of Latin origin, but it reached English via a Celtic route. English borrowed it from Scottish Gaelic pillean, a diminutive form of peall ‘covering, cushion’. This in turn came from Latin pellis ‘skin’ (source of English pelt ‘skin’ and related to English film). => film, pelt[pillion etymology, pillion origin, 英语词源]