(building construction) A door that folds and unfolds like an accordion when it is opened and closed.
1. Any fabric-faced door which is hung from an overhead track and folds back like the bellows of an accordion.
2. A hinged door consisting of a system of panels which are hung from an overhead track. When the door is open, the faces of the panels close flat against each other; when the door is closed, the edges of adjacent panels butt against (or interlock with) each other to form a solid barrier.