Definitions
1.nounA pad behind the saddle of a horse for a second rider.
2.nounA similar second saddle on a motorcycle for a passenger.
3.nounThe person riding in the pillion.
4.nounThe cushion of a saddle.
5.verbTo ride on a pillion.
6.verbTo put a pillion on a horse.
7.adverbRiding behind the driving rider, as when positioned on the rump of a mount.