Shutter

A shutter is a movable cover or screen that alternately prevents and permits the passage of some desirable (or undesirable) element:

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• A window shutter is a door for covering a window, or a decoration of similar appearance added for visual appeal.
• In pipe organs, a shutter prevents or allows air to pass through the pipes, producing the desired sounds.
• A shutter (photography) is a photographic device that administers the exposure by admitting light to the film for a specific period of time.