From Longman Dictionary of Contemporary Englishpillionpil‧lion /ˈpɪljən/ noun [singular] British English TTCthe seat behind the driver of a motorcycle a pillion passenger —pillion adverb Tom had never ridden pillion before.
Examples from the Corpus
pillion• In the past she has gone as a pillion passenger on husband Steve's bike.• The plaintiff was a pillion passenger on a motor bike driven by the defendant.• There must be evidence, usually of the police officer's observations, that there was a pillion passenger.• His pillion passenger is in hospital suffering from shock.• Tom had never before ridden pillion on a motorbike, but Andy the neighbour had a spare crash helmet.• I rode pillion & Bob in the sidecar, because the only spare helmet was too small for Bob.• Once he brought another famous theatrical knight on the pillion.• The pillion passenger is being treated in the Gloucestershire Royal Hospital for abrasions and shock.ridden pillion• Tom had never before ridden pillion on a motorbike, but Andy the neighbour had a spare crash helmet.Origin pillion (1400-1500) Scottish Gaelic pillean or Irish Gaelic pillin, from peall “couch” 