Definition: An interior molding attached to one of a pair of doors or sash in order to prevent swinging through; also used with sliding doors to insure tighter fitting where the doors meet. * Flat astragal - A non-rabbeted astragal applied to swing doors; the astragal is applied to the face of the meeting stile of in of the doors. * Sliding astragal - An astragal to cover the meeting joint of the sliding door. * T-astragal - An astragal, T-like in shape, which is rabbeted to the approximate thickness of the swinging door.