A window replacement for filling a window frame in an aircraft is provided, in particular a passenger aircraft, the window replacement being fixable by a retainer in the window frame in place of the window assembly when the window assembly is removed. The window replacement includes a panel-shaped element with at least a single curvature, the panel-shaped element being made of a synthetic material. The window replacement is formed by a monolithic panel-shaped element. The panel-shaped element of the window replacement may also be formed by a sandwich panel. This allows a weight reduction in comparison with a window replacement of a metallic material.