shutter

n. 1. One who shuts or closes. [ 1913 Webster ]

2. A movable cover or screen for a window, designed to shut out the light, to obstruct the view, or to be of some strength as a defense; a blind. [ 1913 Webster ]

3. A removable cover, or a gate, for closing an aperture of any kind, as for closing the passageway for molten iron from a ladle. [ 1913 Webster ]

4. (Photog.) A mechanical device of various forms, attached to the aperture of a camera lens for opening and closing to expose the plate. It is usually designed so that the time during which the aperture is opened may be varied by a manual dial or by some automatic mechanism, thereby allowing proper exposure of a photographic film under different intensities of light. [ Webster 1913 Suppl. +PJC ]