1) Child-raising technique 2) It can give a child a lift 
This child-safety seat is designed for children who are too large for a baby seat, but not big enough to sit safely in the vehicle's seats.
An object that can be placed on another chair or in a car so a small child can sit higher.
a padded seat that can be placed on a chair seat, for seating a child at the proper height, as at a table or in a barber chair.
a seat to help raise a child in a vehicle so that the vehicle's seat belt fits properly.