(1):

(n.) A mechanical device of various forms, attached to a camera for opening and closing to expose the plate.

(2):

(n.) A removable cover, or a gate, for closing an aperture of any kind, as for closing the passageway for molten iron from a ladle.

(3):

(n.) 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.

(4):

(n.) One who shuts or closes.