From Inga Sempé:
Coussin is a sofa which looks simpathetic and soft and in which one feels good. It was conceived for adults and children. It is simply made of a base bed with a mattress on which is fixed a long cushion, with loose ends which can be put where you desire. It is like being on a bed using pillows under your head, under your feet, wraping yourself into them, or just sitting comfortably. Coussin can be both a nest and a sofa.
(Coussin means pillow in french).