backcushion
nounUK /ˈbækˌkʊʃən/
US /ˈbækˌkʊʃən/
A backcushion is a soft pad you put behind your back to sit comfortably.
She placed a backcushion on her chair before reading.
OTHER MEANINGS
2. A cushion placed against the back of a sofa or seat for decoration.
The sofa came with two matching backcushions.
3. A padded support worn or attached to protect the back.
The car seat had a backcushion for long drives.
4. The rear padded part of a piece of furniture.
He leaned against the backcushion of the bench.