To ride on a pillion.
To put a pillion on a horse.
Riding behind the driving rider, as when positioned on the rump of a mount.
The person riding in the pillion.
A similar second saddle on a motorcycle for a passenger.
The cushion of a saddle.
A pad behind the saddle of a horse for a second rider.
To be a passenger in the pillion of a motorcycle.
To act in a subordinate sense to another.
To be a passenger in the middle seat of a car with two others at either side.