shutter
n. countablen. the part of a camera that opens and closes to let light in when you take a picture. It can also mean the wooden or metal covers on the outside of a window.
n. a mechanical device that opens and closes to expose film or a digital sensor to light for a specific duration. In architecture, refers to a hinged panel used to cover a window for security or light control.
The camera shutter clicks when I press the button.
Using a fast shutter speed allows you to capture sharp images of moving objects without any blur.
The photographer adjusted the shutter to a longer exposure time to capture the soft, flowing motion of the waterfall against the static rocks.
From shut + -er. Compare shuttle.
Often used in the compound 'shutter speed' in photography contexts.